OK Massassians, need more tech help

This is really pissing me off. My parents have been bugging me to fix their computer. When I checked it out it was riddled with viruses and ****. I tried installing Security Essentials but of course it has SP2. So I got malware bytes and it found like 80 things its first scan.

Now I got it all cleared up so I go to install SP3 and of course I keep getting an error Access Denied. My account is an administrator account. SO I boot in safe mode and do the Admin account... Access Denied. WTF

Windows and Program Files had disabled everyone from accessing it so I changed that and added everyone back... still getting the same goddamn error!

I followed some bull **** article that MS had up about restoring Sercury Settings and I tried again as Administrator... guess what SAME ERROR Access Denied. I am ready to format this ***** but they don't want me to since they have all the family photos and **** on there.

Any advise? Or should I just format...

Backup the photos and reinstall. It sounds like the viruses tampered with a bunch of security settings and permissions. You can fix it, but by the time you do you could have just reinstalled.

Security Essentials doesn't run on SP2 anymore? I have it installed on a SP2 machine right now, though it is bugging me for an update.

But yeah don't even dick with it, backup and reinstall the OS.

x3 for backup the pics and wipe it.

Yeah then tell your parents they owe you cause you saved them $300 at geek squad lol.

x5.

Backup the pics, wipe 'er clean and reinstall and update.

ok well why stop here guys

x6, you should back up all the necessary data, then wipe it and reinstall

x7 go buy windows 7

Just to be really sure, reformat, reinstall, and then reformat and reinstall again.

You can't be too sure about these things.

Then, install win7, set them up a normal user account, and don't tell them the admin password.

will do, looks like formatting is in...

thanks guys