CISCO ACS v3.3.3 on windows 2003 sp1

I have two Windows 2003 SP1 boxes running Cisco ACS v3.3.3 . The software
was upgraded from v3.2 as it wasn't listed for support on this OS. After
around 12 minutes of uptime the IP stack falls over leaving the machine not
reachable and recovers after around 3-4 minutes on its own. We have
installed a couple post sp1 patches one being 898060 but nothing seems
address this issue. The boxes are fine if no devices are talking to them
which leads me to believe that the problem comes from something in the ip
packet that SP1 doesn't like. We have 2 older boxes running windows 2000 SP4
and these are fine.

Has any one come across this issue before ?

Any ideas or suggeestions are gladly appreciated.

Thanks

Stuart