Attempting to install Paint.NET 3.5.1 on a brand new clean installation of Windows 7 fails saying that .NET 3.5 SP1 needs to be installed. This is incorrect, since Windows 7 comes with .NET 3.5 SP1 preinstalled. I first suspected that the method used to detect 3.5 SP1 was flawed. However, looking at the official method of detecting the SP version (http://stackoverflow.com/questions/1990 ... -installed), I found that even though Win 7 comes with SP1 preinstalled, the registry value \HKLM\Software\Microsoft\NET Framework Setup\v3.5\SP is still set to 0. There is also a subkey to the v3.5 key called 1033 (the English LCID) which contains a SP value with the right data (1). You may want to check that localized value instead, or else check the Version value for a version number greater than or equal to 3.5.30729.4926.
