I found I weird behavior after I upgraded to 10525 and made a reset. When I run the "cleanup" and remove previous versions of windows, it completes but leaves on the disk the folder "Windows.old". No matter how many times I run the cleanup, that folder always stays. If I try to delete it manually (after I take ownership of it) I get errors telling that files are open. I even reset the SP3 once more but nothing has changed on this behavior.