This didn't happen prior to EV being installed. Full version 7.0.1.2002.0.dcom, Outlook 2003, in cache mode, XP SP2. OST is 5 Gb, but have multiple users with 1-2 Gb having similar problems, just not as prevelant. The problem seems to be, no matter if Outlook is shut down normally or abnormally, it starts running a 'data file check'. Deleted the OST, rebuilt it, worked great for a week, then started doing the same thing again. Drive has been defragged. Complete rebuild of user profle, same results, about a week of usage, then back to running consistancy checks. Any ideas?