somosot

I have a client that has been getting an intermittent error that occured preventing his ost file from being properly saved. Allegedy, this happens at random times even after he's been in outlook for part of the day, so that he has to restart the application to get back into his email. I tried to rename and rebuild the ost file, but I'm still getting the error. He has an Exchange account using outlook 2003 on Exchange 2003.