Reply to Message

While IE8 has added security features, they don't seem geared towards the file system level, they are related to network authentication and heuerstic determination blocking of questionable material.

Your post indicates there are multiple users of the laptop that have admin rights. Might one of those users have accidentally changed FS permissions volume wide? This would also cause free space to drop to nothing as now blocked service accounts log errors exponentially. If this were the case logs will fill up again fairly quickly.

Have you checked Event Viewer? Is there anything suspicious looking?