BSOD watching multimedia over a network

This is the first time I've had BSOD problems on this PC and first time on this forum. It's a custom build and I don't think I installed or updated anything new before the problem started. I get the BSOD randomly. When it happens I usually have Windows Media player playing a show from one of my other machines, and Firefox open, but I don't know if either of those are the causes because it don't occur right away. It could be after watching stuff and browsing the web most of the day before the BSOD. Once after rebooting hot explorer would continually crash, but that has not happened since and after a cold boot everything goes back to normal. It has happened about once a day since mid week last week. Any guidance you could provide would be greatly appreciated.

Thanks for the quick response. Before heading to bed I started up memtest and it's had reported around 20k errors and it was only 3% through the first pass. So it looks like I have some memory situations to work through and if that doesn't fix it I'll go through your suggestions as well.