Since I got guild wars on release, its run pretty well, but in the last week or so, its been freezing more and more. I used to be it might freeze after a few hours of play. Now its freezing after like 30 mins...

When it freezes, it just totally locks up. No error or anything. Computer does not respond, although the game is still on screen, but its frozen. I just have to restart and then it runs fine, for a few more hours if im lucky.....

Anyone have any sugguestions?
I'm pretty computer savy and I know how to keep my computer clean. And I have a decent setup,

2.8 P4,
1 GB pc 3200 of some budget ram. (4*256)

I'm thinking it might be a RAM problem? Ive tested my ram before, and it was fine, but ill run the test again and see what I get. Anyone have any other ideas?