Even after junction points my C: drive can still fill up, what with??? Using the great WinDirStat I was still none the wiser. It turns out the WinDirStat doesn’t see the space taken up with system restore points.
I don’t use them myself, if my system gets so bad I’d rather re-install. Plus I use CrashPlan for my personal data. So if space it tight and you don’t need any system restores then:
Control Panel > System and Security > Administrative Tools/Free up disk space
Choose the C: drive
Click on the Clean up system files button
Choose the C: drive again
This should now show the More Options tab, click on it
In the System Restore and Shadow Copies section click on the Clean up… button
Click on the Delete button to delete all but the latest restore point will be removed. This once freed up 100GB on my new C: drive SSD! I’ve just done it again and freed up 60GB.