You don't give enough information to be sure but it sounds like your are using the registry cleaning aspect of ccleaner, and/or your IT department doesn't have your user profile cacheing correctly so each time you run ccleaner a improperly placed file is being removed and office thinks it is installing a new user.
if the former is true please see my signature
if the latter is true
1 uncheck everything in cleaner (both Windows and Application section)
2 check the first item (temporary internet files)
3 run ccleaner
4 see if office is broken
5 if 4 is no, uncheck the item and check the next one and repeat steps 3-5 until office is broken.
6 when you find the item which breaks office right click on the results and choose save to file