My PC build keeps crashing. I've noticed that it crashes after a new USB device has been connected. I can only connect my iPod, flash drive, printer, or an ext. HD for a few mins before my system crashes. However my mouse, keyboard and remote (all USB) do not cause a crash. I connected an ext. HD with firewire and have had no problems. Also it has been known to crash after extensive use. For example, playing a graphics intense game or video encoding for several hours. I believe the cause to be my mobo or a PSU problem, but I could be wrong. The error report and my system specs are below. Any help would be greatly appreciated. Thanks!

Error:
Error code 1000007e, parameter1 c0000005, parameter2 804f04fe, parameter3 bacfba68, parameter4 bacfb764.

System:
Windows XP Pro
AMD Athlon 64 X2 3800+ 2.01 GHz
2GB OCZ RAM
DFI Infinity Mobo
BFG Tech Geforce 7800GT
Creative X-Fi soundcard
300GB WD Velociraptor
320GB WD Caviar

PSU:
OCZ Modstream 780W Modular
Output: +3.3V@30A,+5V@30A,+12V1@20A,+12V2@20A,+12V3@20A,
+12V4@20A,-12V@1A,+5VSB@3A