Dukethrust has a point on the conflict front: Historically network cards have shared resources with GPUs. This, again historically, has been resolved by eliminating resource conflicts. Granted, this is not supposed to be an issue anymore with the advent of virtual interrupts.
The error you received is quite generic though and could even be related to an unstable overclock, if you have overclocked. Could also be related to memory issues, if you have not already tested for memory errors. There are many potential problems related to your system's symptoms.