Trojans spyware

[rotwilerblue]

guys!

I am really having a problem with my Anti virus protection. I am using three protection; Malwaresweeper (for spyware), Spybot (for spyware) and trendmicro (for Viruses). Before they were all working perfectly. My malwaresweeper detected trojan spyware and backdoor worm even the nugache. Malwaresweeper detected those three but the other two did not. Lately my antivirus was not working well. It could not update. I tried to reinstall the software and update it, it works fine. But as I shut down my PC and comeback the next day. The antivirus does not work anymore.

Do you have any sudjestion or advise to protect my pc? I even use the peer guardian for protect or detection of Malicious software.