cannot access "dimension.xls"

NW 7.5 SP09... After new dimension members are entered in the membersheet, processing dimension works fine but when try to save to the server after processing, it gives an error message stating "cannot access dimension.xls" (Ex:account.xls). If I get out of the membersheet after processing and then come back in and save, it saves without error. Wondering what is going on here?

Tried saving first and then processing, same issue. Same Issue with other dimensions also.