I was having "data file could not be read" problems all of a sudden when I started Outlook 2007 (started today). Running scanpst found errors are made fixes, but did not solve the problem. Doing a search revealed that some people had good luck removing or disabling add-ins which were not installed as part of the OS installation. I took a look and found these add-ins active in Outlook:
Adobe Contribute Plugin
Microsoft Exchange Unified Messaging
Microsoft Office Groove Proxy for Outlook Add-in
Microsoft Office SharePoint Server Colleague Import Add-in
Microsoft Outlook Mobile Service
OneNote Notes about Outlook Items
Outlook Change Notifier
Windows Search Email Indexer
I think Change Notifier is associated with Apple, but not sure if it's either Quicktime or iTunes. I have to assume the Adobe one is for Photoshop, Reader, or FlashPlayer. I'd like to find out for sure where these all come from and whether I lose anything if I decide to disable any of them.
BTW, I did disable Change Notifier and it did seem to fix the data file problem on opening Outlook, but I still would like to know about the rest of these.