Hmm, disk cleanup only yields 0.75 gb, worthwhile but not addressing the bigger issue. Just analyzing with CC too but expect it will show much the same.
Downloaded WinDirStat by coincidence in the meantime after googling and have run that but not sure what the results mean !
It shows the C drive as being 80 gb or so and then lists below it the various folders and their sizes, which I guess are subsets of the 80 gb, in which case it's telling me what I thought at the start, that the Windows Explorer pie chart thing is misleading massively when it says that 270 gb is used ?
I'll take a look at the system restore stuff in a minute if CC doesn't pick it up....
Cheers, Paul