"Security Tool" lock down - unable to complete Avast Scan

[whistlegal]

I'm new here and need some help.  I've gotten a computer virus, I believe.  I don't have a great deal of experience or knowledge with viruses.  I have endless popups from "Security Tool" telling me I have numerous trogans, malware, and viruses and they can clean them for me if I'd just enter my credit card information, which of course I'm not going to do.  I'm locked out of numerous files including "add/remove software" as well as numerous data files.  I purchased the Avast 4.8 Professional Addition, downloaded and activated the software.  Every time I attempt to run the scan, my computer "crashes" at the 53% completed point with a message that I have a PPCMDCOM.SYS error and my computer needs to restart,, which, of course, aborts the scan.  How will I ever clean this virus when the scan can not be completed?

Any help that could be offered would be greatly appreciated.  Again, I am not an advanced user - particularly when it comes to viruses and security issues.

Thanks!

[Pondus]

Remove Security Tool and SecurityTool (Uninstall Guide)
http://www.bleepingcomputer.com/virus-removal/remove-security-tool

[Lava25]

Hi there,
 I have the same virus on my in-laws computer.  Unfortunately I hadn't installed avast yet and it wont let me add/remove hardware, or restore.  I have tried to download malware removal and super anti spyware and it pops up and blocks every time.  Any suggestions?

[Pondus]

Hi there,
 I have the same virus on my in-laws computer.  Unfortunately I hadn't installed avast yet and it wont let me add/remove hardware, or restore.  I have tried to download malware removal and super anti spyware and it pops up and blocks every time.  Any suggestions?

Can you perform step 2 and 3 in the removal guide?

[whistlegal]

Thank you so much, Pondus!  That worked like a charm!  It took a couple of hours for the scan, but the malware is gone, gone, gone!!  I can't thank you enough.

[Lava25]

Thanks so much, I didn't even try it because I assumed it would block that as well as all the others.  Turns out it didn't after trying twice, and it worked like a charm. I think I got it all out and now I will install the Avast program.  Thanks!

[Pondus]

you're welcome