Just a shot in the dark, but here goes....
Systems affected: Windows 7 x64 with Dot Net 3.5 and Dot Net 4.0
I am troubleshooting an interesting problem. We implement a rather complex software solution within our organization. It uses Dot Net 3.5 framework. Occasionally, this software will quit working for reasons that are still unknown. I believe it is directly related to Dot Net 3.5.
My reasoning for this theory; I can remove the 3.5 framework from the "Turn Windows features on or off" area of Programs and Features, then reinstall it and the software will run...,one time only. I can also reboot the PC and the the software will also run one time only.
I have tried a system restore, windows 7 O/S repair, turning off system services one by one, etc. Nothing seems to work. I take that back, if I re-image the afflicted PC, then the problem will go away. Re-imaging does not fix the problem, it only covers it up.
I am hoping that someone might see this post and know what the problem is. If anyone has any further questions, please ask. I want to fix this pesky little problem.