My Vista (64 bit) laptop has been showing messages related to C drive getting full in an unexpected manner. The problem showed its might after quickly nearly filling the added space obtained via re-partitioning. Cleaning disk C, defragmenting, uninstalling programs, removing shadow/restore copies, checking out hibernation & pagefile settings, clearing browser cache, removing old Vista system files no longer required after service pack updates etc. offered temporary respite but did not fix the problem. Eventually, all this turned about to be much ado about nothing when it was discovered that the issue was the inflated C:\Windows\Temp folder. Once the contents inside it were deleted, around 80 GB became free. This folder should have been cleaned by the OS, but that was not the case - reminds me of early Windows days.