Your unexpectedly quick-working forums software just erased my longer message, which had taken me 15 minutes to formulate. Great. This is what actually happened...
Paint.net did not install. Installation aborted without prompt, without error message. Inside task manager the .exes where just gone: .net install replaced paint install, then .net (framework) install disappeared. No warning, no message.
Took me 20 long minutes to look into the paint.net install .exe's file system (unpacked it with 7zip) and found the .net web installer. Ran it. says the following:
The thing is not my PC or its OS, nah...
The thing is, (APART FROM YOUR FORUM EATING UP, no -- throwing into black holes long-developed postings) that the paint.net install neither monitors the .net install nor lifts its invisibility parameter ever.
So, if a mistakes makes .net framework install stop, the user will never see it. That is not good, guys. Two ideas for you:
1st monitor the .net install, grab the error message out of its windows or simply visualize the error window. Good, that's hacky and hard to maintain on a longer scale, so:
2nd (and better)
SET UP A REGISTRY KEY THAT NOTES WHETER .NET FRAMEWORK INSTALLED CORRECTLY - IF IT DIDN'T LAST TIME, START .NET FRAMEWORK INSTALL IN VISIBLE MODE, NOT SILENT.
Come on guys, fix this terrible backdoor for frustration and slight feeling of ignorance-caused brain horror. Fixing this .NET thing on the OS is no problem to someone who can efficiently use paint.net ... but I had to decompress an .exe file !!! Absolute no-go in my opinion.