When I run CCleaner from my Windows XP administrator acct., will it reliably clean other user accts at the same time, such as the guest acct.?, I can see that it cleans the recycle bin, but I I can't tell what it is doing to index.dat, Firefox cache and other invisible but sensitive data.
welcome to the CC forums
it wont clean out everything, to do that you would have to run it on each account.
it may be supported and ingraded into an upgrade.
most of the stuff that its not catching would be in C:/documents and settings/"other user names"/