Silver, who helped me here, recommended I post this problem here.
Months ago I lost the ability to retrieve files from the Temp folders the way I used to:
Control Panel > > Free up space on your hard disk > C: > [Select] Temporary Internet Files > View Files.
"Disk Cleanup for (C:)" always indicates the total size of all the files I expect there to be (sometimes 100s MBs), but the Windows Explorer window is always empty, even when "Show hidden files and folders" is selected.
I can still see the files via IE (IE7 > Tools > Internet Options > Browsing History > Settings > View Files), although I can’t, obviously, view them easily.
I don’t know enough to have tweaked anything to have caused this.
I’d be grateful for any help.