Vista restarts on standby

About 3/4 of the time that Vista goes onto standby, it automatically restarts. Whether I just close the lid of my laptop or it automatically goes into sleep-mode, most of the time I hear the startup ring a minute later. The biggest problem with this, though, is that whenever this happens, it also wipes all of my cookies. I've updated all of my drivers, but that didn't fix the problem. Any ideas?

Anyone?

I'd suggest:
- downloading the latest video drivers available for your system.
- uninstalling the current video drivers through Control Panel...Programs...Uninstall a program
- install the freshly downloaded drivers
- test to see if this fixed the issue.