submit a ticket to Webroot about this error and see if they have a fix.

You can also use DBAN (it's free) http://dban.sourceforge.net/ to wipe the hard-drive. Then fresh install Windows.

If you prefer to not to wipe the hard-drive by keeping the operating system on it, you can use also the freeware CCleaner Freeware http://www.ccleaner.com/ (in case Webroot has no solution or answer yet) to clean-up drive using many passes.