Unknown Virus/Malware preventing most programs from running

[Guest]

[Pambrosio]

Hi, I'm running Windows XP on a dell desktop that is about a year and a half old. Last night when I logged on, I was unable to connect to the Internet. I attempted to run a virus scan using Norton antivirus, but a few seconds after  I started a full system scan, the program closed. When I attempted to open the antivirus program back up, I got a message that I could not access the program. The same happened when I attempted to run a scan in Malwarebytes and using the windows malicious software removal tool. I actually still had the Malwarebytes installation tool and files on my computer, so I reinstalled the program, but had the same problem.

Since I cannot access the internet from that computer, I'm unable to run any online scans to determine what is affecting my computer. Do these symptoms sound at all familiar or is there another way that I could determine what is impacting my system?

Thanks.

[Silent Assassin]

If I were you I'd follow this guy's suggestions: http://www.youtube.com/watch?v=N4lTAgDH9pw&feature=channel_page

[Kyle]

Hello Pamb. Are you using CIS? If you are - please check the event logs.
Comodo -> Defense+ -> Events

[EricJH]

You can hook up the hard drive in another system and let that scan for malware with several scanners.

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