okay, i have been dual boxing WoW with 2 accounts on the same computer for a while now. my computer can easily handle it. (quad core 2.40 ghz, 3 GB ram, 512MB geforce 8800)

all of the sudden (within the past week of so) my computer starts to freeze when i dual box. but it is fine when i only have 1 WoW open
when i open up my second WoW, it gets all laggy and eventually freezes my computer..
after about the 5th time freezing i restarted my computer and i got a "critical error" something about not having enough storage space

i was wondering if it was something with the cache or the WTF folder?

any help would be appreciated, thanks =D