Mail Messages Disappearing

I am running Snow Leopard and the messages in my mail have disappeared, I tried running Time-Machine but that did not retrieve them. The From, Subject, date received and Mailbox all show normal information, but the body of the messages are blank. The same with the different mailboxes I have in the left column.
PLEASE HELP, this is freaking me out.

I may have found the problem.
While digging in the Mail preferences under Accounts, I noticed that "Remove Copy From Server After Retrieving A Message" (after one week) was checked. I have just unchecked it and we'll see if that does the trick.