About 4-5 months ago I had this same problem. I would get on GW...play for 3-5 minutes...and then the game would freeze up and I couldn't do anything. My screen basically freezes up, along with the rest of my PC. The only thing I can do is hit the reset button on my PC.
So I wrote GW support...they didn't help much. A friend told me to check my memory for errors, and it turns out one of my 512 mb sticks had a few errors. OK, so I take it out and run GW on one 512 mb stick. 3-5 minutes later...frozen!
Then my friend told me to run my 512 stick @ PC 2700, which is slower than what it is made to run at: PC 3200.
And by golly, that fixed it! I did get an occasional freeze up, but it would be random...sometimes at 1 hour and sometimes at 5 hrs, and sometimes not at all. And this went on for a few months...I was happy for the most part, except for the long load times with only 512mb RAM.
Now we're caught up. I was getting annoyed with the long load times so I figured I'd replace that 512 stick I took out. So a couple days ago I order a new stick from Newegg and it arrives today.
I add it to my mobo and everything is peachy...except when I run GW. 3-5 minutes into the game, FROZEN!!!
So...this is obviously a memory issue. It doesn't take a genius to figure that out. I can play any other game for as long as I want without it freezing, but why GW?
I don't know what to do really. I'm pretty proficient with computers and I can't see any problem with my PC that would cause GW to crash/freeze up so easily.
Ideas?

UPDATE:
I underclocked my RAM to DDR 333 (PC 2700) speed, and GW doesn't crash anymore.
So, the problem is this: GW doesn't support DDR 400 (PC 3200) speed.
System specs:
Win XP Pro SP2
3.2 GHz P4 Prescott HT, socket 478 (running @ stock)
ASUS P4S800D-X mobo
1 GB (2x512) Kingston PC3200 DDR400 RAM
Western Digital 80 GB 7200 RPM SATA HD
256 MB XFX Geforce 6800GT 256MB 256-bit GDDR3 AGP 8x