Boomerang Settings

I've just about got Vista how I want it. Every now and then I do something which means I have to load or configure another program I used to use, but most of the time I can putter along and get things done. And I rather like my new workplace. Except for one thing.

Settings that I've changed keep reverting back to their previous values. I'm using a network storage device which is based on a Linux processor and uses SAMBA, so I have to modify a Local Security Policy to make it work. I can make the change fine, and the drive works fine for a while. Then the setting flips back to the original value. Similarly, to get Outlook to log on to our Exchange server I've had to add a registry key. Which keeps vanishing.

The only thing I can think of is that the system thinks it is under attack, and puts things back to their safe values. I've had a cursory dig around but nothing out there tells me how to fix it. Very strange.