I’d just found an alternative method here, but now we’ll have to deal with the consequences of the method you tried.
Could you post another HijackThis! log?
Scan your computer using Hijackthis. After scan locate line O20 - Winlogon Notify: win???32 - C:\WINDOWS\SYSTEM32\win???32.dll. ??? [3 questionmarks- the forum is substituting a smiley] is replaced with any 3 symbols (For example: winzdn32.dll). Go to C:\WINDOWS\SYSTEM32\, find win???32.dll file and rename it adding .txt extention (win???32.dll.txt). Restart the computer.
http://www.spyware-removal-guideline.com/win-tmp-exe-popups-removal
This obviously fits the description you provided, as win1F.tmp.exe was a symptom.