Malware Protection Shutting Off????

First time poster here!
Thanks for having me....
My old pc was hacked/attacked/destroyed by a virus, keylogger,data thief...aaarrrggghhh.
I have just purchased a new desktop that came with Windows Vista Home Premium 64 bit OS. Here's my issue.

When I log off -shut down my pc & log back in, the Malware Protection @ the Security Center has been turned OFF.

Does anyone have any idea as to why this is happening? I scan as soon as I sign in and this is scaring me to death, especially after what happened to my old pc. The Firewall was constantly "being" turned off old pc.

I was using the highly recommended Trend Micro IS 2008 on my old PC and am now using McAfee through MSN Premium.
I am a novice user and would appreciate any help tips or useful info I can get.
Thanks
Kj

Try & run an online scan & check if the system is infected or not. And if it is not infected you can try to uninstall & then re-install Mcafee.

I will do that straight away!
Thanks so much tanuj_chadha