BleepingComputer.com: System appears to be in an endless search mode

HI

This morning I found my computer had not gone to sleep (monitor off). On clicking the "start" button I discovered the search function was continually searching with the pattern of..... zzzzzzzzzzzzzz. It would not allow me to access any of the menu items except shut down which I tried but found it was taking too much time to begin closing down. I manually had to turn it off at the power point. On start up it asked whether I wanted to start normally or in safe mode. i selected normal. Again on start up the problem was still there. I again powered off the PC (NEC) at the GPO. On start up selected Safe start with DOS option but this time on start up when I went to the admin logon the computer put in a full line of asterix's automatically. I immediately powered off the PC and this time selected Normal for start up. When I tried to login as the Administrator it did not recognize my password. The computer had not been connected to the internet overnight or during this time but I suspect somehow it has been given a trojan or a virus possibly when connected to the Net. I have Zone Alarm enabled with it's virus protection (paid version) and update the virus dats regularly.
Has anyone expierenced this or know of a fix. I suspect I will need to do a disk wipe and clean install of Vista and personal programs.

Try starting in normal mode and right-click on the Task Bar and open Task Manager
In the Applications window terminate any task that is running
Then click on the Start a new task button and type explorer.exe and OK
Do you have your Desktop now?

Thanks Booted up normally tried admin password a couple of times - it worked second time round. Checked using Adware found over 200 boogies - all seems ok now