paint.net started refusing to open on my system two days ago. I was getting the "Paint.net has encountered a problem and needs to close." error message as soon as I attempted to open it. I tried reinstalling paint.net, but then received an error stating "Paint.net Front End Loader has encountered a problem and needs to close" when I tried starting Setup. (I'm not 100% sure that it said Front End Loader, but it was something similar.) So...I couldn't install paint.net.
I read through much of the information regarding this problem on this forum, but nothing helped. I reinstalled .NET 2.0 to see if this would correct the problem, and it didn't. I just ran Windows Update, which installed .NET 2.0 Service Pack 1 and I was then able to install paint.net.
I haven't noticed any information telling people to make sure that they have .NET 2.0 Service Pack 1, so I thought I would share this information, in case it might help anyone else...
