What, again? Michael stared at the Explorer window in disbelief. The free disk space bar was glowing red, and the text underneath reported that his half-terabyte system partition had a measly few gigs left before filling up.
When it had first happened, he hadn't thought twice about it. In fact, he'd been rather glad; at least he'd had the motivation to finally discard all the games and software he would never use again. But when the disk space ran out again the next month, and again the month after, he started getting more and more worried. Was he really using that much space, or was something else going on?
Curious, he decided to finally investigate the issue. A cursory look at his hard drive with WinDirStat confirmed his suspicions. With over 80 percent of his hard drive space labelled as "unknown", something was definitely amiss. He kept searching, manually scouring through his folders and files, until finally he managed to pinpoint the culprit: an innocuously named "C:\Windows\System32\Config" folder filled with hundreds of thousands of files, taking up 420 gigabytes in size.
A quick trip to Google and a bit of playing with Process Monitor revealed the answer to the mystery. As it turned out, every modification to Windows Registry—the oft-derided database of all the Windows and Windows application settings—generated a transaction log file to ensure the data integrity, prevent corruption, and allow rollback of changes. Usually those small 512KB files weren't much of an issue. They got deleted after a clean reboot, and most software only modified the registry during installation or after a configuration change.
However, some applications and drivers—among them, Nvidia's 3D service—didn't play nice with the registry, shuffling the values around every few seconds or minutes. That, together with Michael's habit of not turning the computer off too often, resulted in cluttering the disk with more and more files until it filled up completely.
The solution, luckily, was rather simple. Michael purged the folder of all but the most recent log files, then uninstalled all the unnecessary bloatware from Nvidia, hoping it was the last thing he'd be deleting for a long while.