I upgraded my Ubuntu server to 14.04 and Apache 2.4.7.
Now my images don't load and console yields net::ERR_INCOMPLETE_CHUNKED_ENCODING. Also, I can sometimes see some of the images load for a little while (1 sec max) and then they disappear. .htaccess

RewriteEngine On

# Serve the favicon file from img folder
RewriteCond %{REQUEST_URI} ^/favicon.ico$
RewriteRule ^(.*)$ /img/$1 [NC,L]

# Redirect HTTP traffic to WWW subdomain
RewriteCond %{HTTPS} off [NC]
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

# Redirect HTTPS traffic to WWW subdomain
RewriteCond %{HTTPS} on [NC]
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^(.*)$ https://www.%{HTTP_HOST}/$1 [R=301,L]

# Auto Versioning rules
RewriteCond %{REQUEST_FILENAME} !-s
RewriteRule ^(.*)\.[\d]+\.(css|js)$ $1.$2 [L]

# Default Zend rewrite rules
RewriteCond %{REQUEST_FILENAME} -s [OR]
RewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^.*$ - [NC,L]
RewriteRule ^.*$ index.php [NC,L]

VHost

<VirtualHost *:80>

    ServerAdmin admin@localhost
    ServerName localhost

    DocumentRoot /home/mihai/ARTD/www/public/website

    # Omit this in production environment
        SetEnv APPLICATION_ENV local

    <Directory /home/mihai/ARTD/www/public/website >
        Options Indexes FollowSymLinks MultiViews
        AllowOverride All
        #Order deny,allow
        #Allow from all
        Require all granted
    </Directory>

    <IfModule mod_php5.c>
        php_value memory_limit 128M
        php_value upload_max_filesize 20M
        php_value post_max_size 20M
        </IfModule>

    ErrorLog /var/log/apache2/ARTD-error.log

    # Possible values include: debug, info, notice, warn, error, crit,
    # alert, emerg.
    LogLevel warn

    CustomLog /var/log/apache2/ARTD-access.log combined

</VirtualHost>

<IfModule mod_ssl.c>
<VirtualHost *:443>

    ServerAdmin admin@localhost
    ServerName localhost

        DocumentRoot /home/mihai/ARTD/www/public/website

        # Omit this in production environment
        SetEnv APPLICATION_ENV local

        <Directory /home/mihai/ARTD/www/public/website >
                Options Indexes FollowSymLinks MultiViews
                AllowOverride All
                #Order deny,allow
                #Allow from all
        Require all granted
        </Directory>

        <IfModule mod_php5.c>
                php_value memory_limit 128M
                php_value upload_max_filesize 20M
                php_value post_max_size 20M
        </IfModule>

        ErrorLog /var/log/apache2/ARTD-ssl-error.log

        # Possible values include: debug, info, notice, warn, error, crit,
        # alert, emerg.
        LogLevel warn

        CustomLog /var/log/apache2/ARTD.log combined

    #   SSL Engine Switch:
    #   Enable/Disable SSL for this virtual host.
    SSLEngine on

    #   A self-signed (snakeoil) certificate can be created by installing
    #   the ssl-cert package. See
    #   /usr/share/doc/apache2.2-common/README.Debian.gz for more info.
    #   If both key and certificate are stored in the same file, only the
    #   SSLCertificateFile directive is needed.
    SSLCertificateFile    /etc/ssl/certs/ssl-cert-snakeoil.pem
    SSLCertificateKeyFile /etc/ssl/private/ssl-cert-snakeoil.key

    #   Server Certificate Chain:
    #   Point SSLCertificateChainFile at a file containing the
    #   concatenation of PEM encoded CA certificates which form the
    #   certificate chain for the server certificate. Alternatively
    #   the referenced file can be the same as SSLCertificateFile
    #   when the CA certificates are directly appended to the server
    #   certificate for convinience.
    #SSLCertificateChainFile /etc/apache2/ssl.crt/server-ca.crt

    #   Certificate Authority (CA):
    #   Set the CA certificate verification path where to find CA
    #   certificates for client authentication or alternatively one
    #   huge file containing all of them (file must be PEM encoded)
    #   Note: Inside SSLCACertificatePath you need hash symlinks
    #         to point to the certificate files. Use the provided
    #         Makefile to update the hash symlinks after changes.
    #SSLCACertificatePath /etc/ssl/certs/
    #SSLCACertificateFile /etc/apache2/ssl.crt/ca-bundle.crt

    #   Certificate Revocation Lists (CRL):
    #   Set the CA revocation path where to find CA CRLs for client
    #   authentication or alternatively one huge file containing all
    #   of them (file must be PEM encoded)
    #   Note: Inside SSLCARevocationPath you need hash symlinks
    #         to point to the certificate files. Use the provided
    #         Makefile to update the hash symlinks after changes.
    #SSLCARevocationPath /etc/apache2/ssl.crl/
    #SSLCARevocationFile /etc/apache2/ssl.crl/ca-bundle.crl

    #   Client Authentication (Type):
    #   Client certificate verification type and depth.  Types are
    #   none, optional, require and optional_no_ca.  Depth is a
    #   number which specifies how deeply to verify the certificate
    #   issuer chain before deciding the certificate is not valid.
    #SSLVerifyClient require
    #SSLVerifyDepth  10

    #   Access Control:
    #   With SSLRequire you can do per-directory access control based
    #   on arbitrary complex boolean expressions containing server
    #   variable checks and other lookup directives.  The syntax is a
    #   mixture between C and Perl.  See the mod_ssl documentation
    #   for more details.
    #<Location />
    #SSLRequire (    %{SSL_CIPHER} !~ m/^(EXP|NULL)/ \
    #            and %{SSL_CLIENT_S_DN_O} eq "Snake Oil, Ltd." \
    #            and %{SSL_CLIENT_S_DN_OU} in {"Staff", "CA", "Dev"} \
    #            and %{TIME_WDAY} >= 1 and %{TIME_WDAY} <= 5 \
    #            and %{TIME_HOUR} >= 8 and %{TIME_HOUR} <= 20       ) \
    #           or %{REMOTE_ADDR} =~ m/^192\.76\.162\.[0-9]+$/
    #</Location>

    #   SSL Engine Options:
    #   Set various options for the SSL engine.
    #   o FakeBasicAuth:
    #     Translate the client X.509 into a Basic Authorisation.  This means that
    #     the standard Auth/DBMAuth methods can be used for access control.  The
    #     user name is the `one line' version of the client's X.509 certificate.
    #     Note that no password is obtained from the user. Every entry in the user
    #     file needs this password: `xxj31ZMTZzkVA'.
    #   o ExportCertData:
    #     This exports two additional environment variables: SSL_CLIENT_CERT and
    #     SSL_SERVER_CERT. These contain the PEM-encoded certificates of the
    #     server (always existing) and the client (only existing when client
    #     authentication is used). This can be used to import the certificates
    #     into CGI scripts.
    #   o StdEnvVars:
    #     This exports the standard SSL/TLS related `SSL_*' environment variables.
    #     Per default this exportation is switched off for performance reasons,
    #     because the extraction step is an expensive operation and is usually
    #     useless for serving static content. So one usually enables the
    #     exportation for CGI and SSI requests only.
    #   o StrictRequire:
    #     This denies access when "SSLRequireSSL" or "SSLRequire" applied even
    #     under a "Satisfy any" situation, i.e. when it applies access is denied
    #     and no other module can change it.
    #   o OptRenegotiate:
    #     This enables optimized SSL connection renegotiation handling when SSL
    #     directives are used in per-directory context.
    #SSLOptions +FakeBasicAuth +ExportCertData +StrictRequire

    #<FilesMatch "\.(cgi|shtml|phtml|php)$">
    #   SSLOptions +StdEnvVars
    #</FilesMatch>

    #   SSL Protocol Adjustments:
    #   The safe and default but still SSL/TLS standard compliant shutdown
    #   approach is that mod_ssl sends the close notify alert but doesn't wait for
    #   the close notify alert from client. When you need a different shutdown
    #   approach you can use one of the following variables:
    #   o ssl-unclean-shutdown:
    #     This forces an unclean shutdown when the connection is closed, i.e. no
    #     SSL close notify alert is send or allowed to received.  This violates
    #     the SSL/TLS standard but is needed for some brain-dead browsers. Use
    #     this when you receive I/O errors because of the standard approach where
    #     mod_ssl sends the close notify alert.
    #   o ssl-accurate-shutdown:
    #     This forces an accurate shutdown when the connection is closed, i.e. a
    #     SSL close notify alert is send and mod_ssl waits for the close notify
    #     alert of the client. This is 100% SSL/TLS standard compliant, but in
    #     practice often causes hanging connections with brain-dead browsers. Use
    #     this only for browsers where you know that their SSL implementation
    #     works correctly.
    #   Notice: Most problems of broken clients are also related to the HTTP
    #   keep-alive facility, so you usually additionally want to disable
    #   keep-alive for those clients, too. Use variable "nokeepalive" for this.
    #   Similarly, one has to force some clients to use HTTP/1.0 to workaround
    #   their broken HTTP/1.1 implementation. Use variables "downgrade-1.0" and
    #   "force-response-1.0" for this.

    #BrowserMatch ".*MSIE.*" \
    #   nokeepalive ssl-unclean-shutdown \
    #   downgrade-1.0 force-response-1.0

</VirtualHost>
</IfModule>

logs

Apache/2.4.7 (Ubuntu) PHP/5.5.9-1ubuntu4.3 OpenSSL/1.0.1f (internal dummy connection)
127.0.0.1 - - [25/Aug/2014:13:09:53 +0300] "GET /img/header/top-nav-separator.png HTTP/1.1" 200 462 "https://localhost/art" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.132 Safari/537.36"