i may have a simple solution that might fix most if not all of your problems ive been getting this error on and off since release i used to be able to just run a repair tool after the updates and it would semi fix it but now it just doesnt work well today i was trying to run an instance and it just kept kicking me off line so i got a little kitten so i did some fooling around in the properties and changed the compatibility to vista service pack 2 and normally i would get massive lag then crash but with vista sp2 you get the random massive lag but it doesnt disconnect you it for some reason pulls back like i said this worked for me i dont know if it will work for you guys its been running for about 3 hours straight now without a crash.
i still think arena net needs to figure out this problem fast cause it really is annoying
(and right after i posted this i finally crashed so yeah they need to fix this)