I have myself encountered this problem a couple of times now, not on any of my systems though. Unfortunately the problem had surfaced on systems of my clients running my software. I've tried every trick known to me and suggested by very well-intending helpful folks. The myraid of things have tried to fix the error start from repairing the framework, uninstalling and then reinstalling the framework to adding the service pack patches (SP1, SP2). Nonetheless the error persist. Once, I installed dotnetfx 3.5 and the problem went again only to surface days later. I'm begining to think its some sort of virus attach on the framework or something. I've checked msdn and can't find any different answers from those I've received from many, different forum. This is a very serious problem for the only way the problem really goes away is by formating the system and reinstalling everything over again. My clients patience is wearing thin. Besides I can't ask them not to go on the internet with their system nor use a flash on the system. Please the dot net MVP's should take a serious look at this. I've waited several months hoping the solution we'd be posted someday on the forum. Nah! Sadly my app is begining to get the reputation of crashing once the Iternet is accessed! HOW TRUE?