Vista - Customize Start Menu & Reverts back

Hi,

I have a problem that has just appeared recently where the Start Menu keeps reverting back to different settings from what I had. I always just had Personal folder, Help & Support and Default Program on my list. Now I also have Computer, Control Panel, Documents, Downloads, Games, Music, Network, Pictures, Run Command and Videos added to it. I have customised the menue and it looks fin, but 10 minutes later if I check, it has reverted back to the extensive list. How do I get it to stay off.

Thank you.

L.