OK, try this:

Go to the TOOLS -> SEND/RECEIVE -> SEND/RECEIVE SETTINGS -> DEFINE SEND/RECEIVE GROUPS menu -- the shortcut for this is CTL-ALT-S. You should have at least one send/receive group called ALL ACCOUNTS. Select this entry, and click EDIT. Now, for each account you have set up in Outlook, you'll have a selection on the left side. Select your account, and under the FOLDER OPTIONS area of the edit menu, there should be a radio-button setting for either DOWNLOAD HEADERS ONLY or DOWNLOAD COMPLETE ITEM INCLUDING ATTACHMENTS. See if this is set for HEADERS ONLY - if it is, changing to COMPLETE ITEMS will most likely solve your problem.

Again, good luck!