My Outlook is forcing rebuild every few days.

Now, when i access an old e-mail and reply to it, it appears on top, as it was received at the time i replied to the message. the message shows the right date stamp, but Outlook indexes it this way...

Had a problem before, where some messages where indexed by Outlook as having been received on the year 2021!!!! that stopped after one of the rebuilds, but now this new problem...

Could anyone help, please?

IOSX 10.9.3

OUTLOOK for MAC 2011