i think i have a virus because on logon screen "startup" an empty window appears when i click ok i can log on to my session .. but why does does it appear ! my PC is infected !
Disable System restore.
Clean the file hosts over replacing it: http://virusinfo.info/showthread.php?t=61042
Remove TuneUp.
Update the version of your antivirus program.
The log shows nothing suspicious.