My Computer has a blue shield with a question mark that periodically changes to a shield with a red X?

First, CLEAN your system restore so malware can't come back. Right-Click "My Computer' and select Properties. Under the "System restore' tab, check 'disable.' Then Try Spybot s/d. Superantispyware free. and an online scan @ bitdefender.com

SmitFraudFix

http://siri.geekstogo.com/SmitfraudFix.php

How to use SmitFraudFix

http://www.geekstogo.com/forum/How-to-use-SmitFrau...

*SmitFraudFix is a tool that S!Ri created to remove rogue anti-spyware applications that utilize Trojans to issue fake

taskbar security alerts or that change your background in order to scare you into purchasing the full commercial version of their software..

These infections are difficult to remove and are usually bundled with so much other malware,

that traditional antispyware or antivirus programs have difficult completely cleaning these infections.

Due to this a specialized tool was created in order to help a user clean their system of these infections.

I believe it is called

Microsoft Security Suite - that is warning you ABOUT something. Click it and find out.

Or it can be one of these

Anti Spyware Pro

Anti Vuris Pro

or one of thier sisters.. ROUGE

But if i was a betting man, I'd bet the first...

Your computer maybe infected with adware.

Try New GarbageClean antispyware from http://www.securemywindows.com/

It is web based and doesn't require installation and it is completely free.

don't worry about it it's just telling u that u don't have a virus prgram but it's ok i have that to just ignore it i've had my comp for 4 years