Just a few days ago, one my clients had several strange problems manifest simultaneously. After a bit of research it turned out that a new patch for .NET 2.0 Framework was the culprit. In the process of updating it had somehow corrupted the entire framework.

Strangely it does not affect all users, but only a select few. If you find that your Quickbooks or UPS Worldship are suddenly inaccessible, it's likely you were affected by this issue. Fortunately there is a rather simple fix - at least until MS releases a patch to fix their first patch!