pxh1pa64 sys

I have been running x64 Vista for a few weeks now. I went to work the other day and came home, the computer wouldn't connect to the network. I checked everything and found nothing so I preceded to do a reboot, just as a standard thing. Hadn't installed anything new hardware wise since I started vista and hadn't installed anything for a few days prior software wise. Have done a couple of reboots since then with no problem. Now I am getting an error saying that it is unable to hash: \windows\system32\drivers\pxh1pa64.sys as I am booting up. It wont let me boot the rest of the way. I do the system restore and then the startup recovery thing and it says that it cannot be fixed by the DVD. I dunno what else to do and I can't find anything on here. Any help would be much apprecieated.