Using excel XP and Win ME. Open a file, make changes, and then try to save as a new file name, computer locks up. Usually have to hit Cntrl-alt-delete and shut excel down to get working again. Auto-Save saves just fine. Its a fairly long file name, but no unallowed characters involved. I've downloaded all the updates from Micorsoft, but no success. One other thing, when using save as and putting in the name of a file that already exists, the screen that prompts to replace an existing file comes up behind the excel program.