What's happening to ML

All of a sudden when I start ip my iMac the Dock icons do not show what they are, the magnification does not woek, the cursor changes back to an arerow insted of the hand it used to be and sll sorts of other things are happening every time I start up. The starup chime qorks sometimes and then it doesn't etc etc. Do I need to reinstall ML or clean instsall it? I upgreded to iPhoto 11 the other day but that seems to be workiong fine. It just seems like I have a new quirk every time I start up and it is becoming very annoying to say the least. If I restart twice everything works fine. I have zapped the PRAM and repaired Permissions several times to no avail. Any clues out there?

iMac 320 GB Hd, 5 gb Memory, ML from LIon from SL.