I tried paint .NET and got two problems, not related directly to the program:
1. After I installed paint .NET 2.6 RC1 and NET FW 2.0, I noticed that System Restore was keeping only a few (one or two) restore points, not the 15+ points it kept before. Perhaps each restore point became too large?
I uninstalled Paint .NET and FW 2.0 and System Restore came back to normal behavior (15+ restore points).
2. Paint .NET updated automatically from the Web, but afterwards I could not uninstall it. It reported a missing file or something like that.
I have NET FW 1.1 installed also.