When I try to delete them or move them into a folder, Paint.net no longer works. I've tried installing new versions of Paint.net, then deleting the files, but it doesn't work. Can anyone help?

Delete paint.net and get the superior gimp-no problems there

But if i had to guess i think you're putting it in the wrong place when installing, make sure it's in C://program files wih the rest of your software

If it's in the right place do dis:
If you have problems downloading Paint NET, please try to stop using your download manager and avoid right clicking on files. Also, check your firewall settings, because some mirrors may require that you do not block the HTTP referers. For further information please read our Downloading FAQ & Guide

Thanks, now my computer's a lot faster!