backed up my data before the weekend, reinstalled (clean install) OS X, and restored the data. Now I am getting the occasional message in Mail sayin something along the lines that "the current mailbox could not be compacted (possibly due to lack of disk space) and that it would now attempt a recovery from teh previous data", or something along those lines. I have multiple mailboxes, and the one affected appears to be my Yahoo mailbox. Messages that I intended to reply to have just disappeared. Can't find them anywhere! I also experienced partially downloaded messages from teh same Yahoo account. Saw the header, but after clicking on it, get a message saying something like "the message was not fully downloaded. Change teh status of teh mail box to online and try again". Problem is: the mailbox was online, and even after quitting and restarting mail, the messages were not downloaded. Logged into Yahoo Mail on Safari, checked the messages as unread and tried again - still no luck. Eventually had to forward them to my .mac account. Biggest problem though, and theone I really need to some advice on is the first one outlined above. Thanks all. Had some important messages disappear on me.