I have Windows XP Home SP3 with Windows Defender definition 1.71.2204.0 dated 14/01/10. I also have AVG, Spybot and AdAware. I have used these for a couple of years without problems. About 2 weeks ago I noticed that when switching on my computer in the morning Windows Defender has somehow been turned off and I have to turn it back on again each morning. I have never had to do this before. What could have happened and how can I rectify this problem?