7-zip is not a Microsoft program. Since it's an open source third party program suggest you seek assistance from "7-zip" if you're having difficulties with the program.
http://www.7-zip.org/support.html
If you continue to have malware issues suggest seek advice from your antimalware provider (Avast, AVG, McAfee, Norton, etc).
Alternatively you may wish to run several of the following free scanners which will not interfere with your installed antimalware program:
AdwCleaner
http://www.bleepingcomputer.com/download/adwcleaner/
Malwarebytes Free: http://www.malwarebytes.org/products/malwarebytes\_free/
Hitman Pro Trial Version: http://www.surfright.nl/en/hitmanpro
TDSS Killer: http://support.kaspersky.com/5350?el=88446
ESET Online Scanner: http://go.eset.com/us/online-scanner
MS Safety Scanner: http://www.microsoft.com/security/scanner/en-us/default.aspx
Regards...