Warning, alerts, Protection are a good thing though.
Most likey if you had had one there wouldnt be a problem now ?
There are several free programs to choose from that dont take unessesary resources available
Line 57 to the right "Restore the Run Command" on
Line 267. Restore "Turn Off and Log Off" - Start Menu
http://www.kellys-korner-xp.com/xp_tweaks.htm
Please do install an av and keep it running at all times.