Spybot S&D has this nifty little aspect called a TeaTimer. It maintains your system's settings. If you already have Spybot, enable the TeaTimer, or get it here - http://www.safer-net...rors/index.html
Oh, and you can reinstall MSAS (Microsoft Antispyware), and when you install it, it should prompt you for the very option your concern is about.
Personally, I don't like the program, it uses a lot of resources. If you scan regularly with Lavasoft Ad-Aware (the personal edition is free) and an Antivirus program (CA eTrust EZ Antivirus is my personal favorite), then you don't need such a behemoth running in the background. =]
Hope this helps.
Edited by Seven!, 01 January 2006 - 02:38 AM.