Strange possibly rogue antivirus taking over avast!?

Ok, well, I was on my PC and one day I see some bs about Windows Defender. I never remember installing or downloading Windows Defender so I can only assume it’s a rogue antivirus. Since then, my avast! has been going a little wacky. There are 3 or so of my constant shields that won’t run. Also, I occaisonally get this message from the probably rogue antivirus saying that my hard drive/disk (can’t remember) might possibly go down and I could lose all of my data. Any information on this? I’m worried this virus might attack my hard drive and delete all of my files and what not!

EDIT:
The message popped up again and it actually shows no signs of the Windows Defender that mysteriously appeared. My hard disk might just be going bad. I did a google search for some key terms in the message and I’m now a bit more optimistic that it’s actually a hard drive problem. If so, I have plenty more but I guess I should back up, huh? I’ll get on that now!

welcome to the forum.

i suggest you download install and scan with malwarebytes antimalware as a first opion.

http://filehippo.com/download_malwarebytes_anti_malware/ don’t forget to update.

then i suggest you do a scan with hijack this and post the result here.

http://filehippo.com/download_hijackthis/

good luck and let us know one the progress.