Same problem with XP SP2
I tried to update to 3.5.1, it quitted around 30% of net.framework
the 3.36 version did not work any more
pdnrepair created an empty logfile
I got this window
Reinstallinitg did not work
deleting net.framework 1.1,2.2,3.0 did not help. they would not re-install properly
I tried Windows Installer Cleaner to no avail.
Restoring to a date before the problem did not change anything, 3.36 did not work ,
I got the same window as mentionned above
I have A-squared Anti Malware, It does not detecte any virus.
Help, please, I am stymied. I loved Paint.net,I can't do without it