After I tried this I didn't have single crash for over month now, before that it was either 1.5 hour idle game crash time or crashing to desktop after every 5th or 6th loading screen usually after switching from one char to another, hope it will work for you guys as well.
To enable the 3GB switch on Windows Vista™ or Windows 7:
1 . Right-click Command Prompt in the Accessories program group of the Start menu. Click Run as Administrator.
2. At the command prompt, enter "bcdedit /set increaseuserva 3072"
3. Restart the computer.
Yeah, add me to the list of people that this has worked for (Win 7 32bit system on a wifi network). In about 5 hours of play this evening, not one ctd. Before using this, one ctd within the first 1.5-2 hours, then one every hour after that.
Thank God for the community, cause the devs seem to be spitting into the wind. Unbelievable.
EDIT: To reiterate a previous statement, I don't consider this a "fix" for BW's problem, but it's as close to one as possible until a fix is issued. Many users don't peruse the forums to come across work-arounds like this, so it still needs to be fixed for them. Meanwhile, the end-users just owned BW in my book.