Message in Log (german):
****************** Sophos Anti-Virus Protokoll - 23.11.2011 12:16:07 **************
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"C:\Users\basal\downloads\portableapps.com_platform_setup_2.0_pre-release_4.2.exe" weist verdächtiges Verhaltensmuster 'HIPS/RemFileMod-002' auf.
Keine Maßnahme ergriffen.
Wenn Sie die Anwendung nicht mit Sicherheit zulassen können, senden Sie ein Sample an Sophos.
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Download was run today. Installation was successfull.
Updates from 23.Nov. '11, 13:11.
Windows 7 SP1 with current updates.
I found only older postings or postings for other versions.
You may have had a false positive in Sophos definitions temporarily or something else on your PC infected it. The installer is clean in all antivirus applications including Sophos as of right now and 3 weeks ago.
Sometimes, the impossible can become possible, if you're awesome!