system security 2009

This week my parents computer wouldn't let them open itunes. A few days later I tried to get online with it and nothing on the desktop would open. when you first log in (after the computer starts up and displays all the users) this system security 2009 pop up shows. I briefly read the self help fix posted on this site, but when I was not able to get online to acquire malwarebytes I thought it best to seek help before proceeding. The computer a compaq pressario desktop running vista. Is there any way to fix this without wiping out the hard drive? thank you for any insight on saving it.

Take a read through this and then start a fresh thread in this forum and post a HJT log, and a brief description of your problem and somebody will be along as soon as.
Helpers look for posts with zero replies which is why you need to start afresh and why i'll lock this one.