I need help with System Security 2009 : Malware

[drgnrose24]

Hello. I'm not sure where this should go, but anyway.... I was on my mother's computer when suddenly System Secrurity 2009 somehow installed itself. I tried to use Malwarebytes to remove it and then in the middle of the scan the whole computer shut down. I booted it back up and now anytime I try to open something a System Security message pops up and says it is infected. This type of thing has happened to us a few times before (with Antivirus 2009 for example) so she downloaded Malwarebytes. How do I get rid of it now...it won't let me open any programs at all. I was thinking maybe I could put her hard drive into my computer as a slave and use mine to scan hers, ( I use Spybot - Search and Destroy) but I don't know if that would make it spread to my computer??? Any suggestions?