I've a virtual machine on VirtualBox 4.1.4 with Ubuntu 11.04. It was working perfectly, but after a reboot something really wrong happened: I wasn't able to connect to the internal network (same for NAT).

$ sudo dhclient -v
Internet Systems Consortium DHCP Client 4.1.1-P1
Copyright 2004-2010 Internet System Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Error creating socket to list interfaces; Permission denied
Can't get list of interfaces.

The network interface is PCnet-FAST III.

Additional information:

$ uname -a
Linux LinuxFileServer 2.6.38-8-generic #42-Ubuntu SMP Mon Apr 11 03:31:50 UTC 2011 i686 i686 i386 GNU/Linux

Any ideas?

Thanks

EDIT:

$ sudo ifconfig -a
eth1      Link encap:Ethernet  HWaddr 08:00:27:af:f2:c7  
          indirizzo inet6: fe80::a00:27ff:feaf:f2c7/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
          collisioni:0 txqueuelen:1000 
          Byte RX:0 (0 B)  Byte TX:3870 (3.8 KB)
          Interrupt:10 

lo        Link encap:Loopback locale  
          indirizzo inet:127.0.0.1  Maschera:255.0.0.0
          indirizzo inet6: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:16 errors:0 dropped:0 overruns:0 frame:0
          TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
          collisioni:0 txqueuelen:0 
          Byte RX:960 (960.0 B)  Byte TX:960 (960.0 B)