Every so often requests to a Linux server (say, linux.example.org) where the web app (Django) pulls in data from a SQL Server database via FreeTDS will hang.

Requests on other servers pointing to the database still work, as do requests on linux.example.org that use local MySQL databases. Only the server plus FreeTDS appear to be affected.

Restarting httpd makes the database connections work correctly again.

What could cause this problem?

Using: Centos 5.9 freetds 0.91 Apache httpd 2.2.3

/etc/obdc.ini:

[DSN]
Description = SQL Server 2005
Driver      = FreeTDS
;Database   = dbname        
Servername  = SERVERNAME
;TDS_Version    = 8.0

/etc/freetds.conf:

[SERVERNAME]
driver = /usr/lib64/libtdsodbc.so
host = db.example.org
port = 1433
tds version = 8.0
client charset = UTF-8