A few people I know are running Outlook 2007 and having this same problem. Where for no apparent reason the data file becomes damaged. Outlook is able to repair, but their appears to be no really reason why the data file is becoming damaged, other than possibly leaving the program in memory or doing a shutdown without waiting for the program to completly shutting down. It doesn’t make any sense though.

There may be other reasons that are causing this.

I can tell you this: I had exactly the same problem as you described. On the internet I found a message about ‘plugins’. This triggered me to look in Outlook 2007 at Extra > Security Center (mine is in Dutch, so I’m not sure this is the correct translation). In the section ‘plugins’ (2nd option) I saw a plugin related to synchronisation with my Iphone. I already de-installed the I-tunes on my PC, but did not de-install the Apple Syncrhonisation software, which can be found in Start > Settings > Software. After removing this program the problem was completely gone! After two months of irritation I now work with great joy with Outlook again. Hope this will help you or anybody else!