Excel 2011 crashes when I work on a large Excel file

There is clearly a bug in Excel 2011 for files on the Desktop where Excel does not clean its scratch files during editing and quitting. Like you, only rebooting seems to get rid of them. The only workaround I have sorted out is to simply not edit Excel docs on the Desktop. I have not seen any data loss issues related to those files on the Desktop.

First, make sure that you're up-to-date with your Outlook updates. The most recent version of Outlook is 14.3.2.

One relatively easy option would be to remove your Exchange account from Outlook, quit Outlook, quit the Database Daemon, and then launch Outlook and re-add your Exchange account. Another option would be to create a new user account on your Mac and add your Exchange account to Outlook there. In either case, this will tell you whether this is an issue with something on Exchange or if it's local to Outlook.

There are additional troubleshooting steps available in this Outlook:Mac KB article, but the steps above are where I would start because they're the easiest.