i dont know what happened (macbook help)

so, i left my macbook plugged in and on all day long the other day.. came home.. my screen was black with just the arrow in the middle (i wanted to stay logged into ichat) but for some reason it wouldn't let me log back on. so i had to hold down the power off button for what seemed like longer then usual, and it wouldn't let me turn it back on until i unplugged the charger.

i dont know if the following has anything to do with the above but this is when it all started.

so i turned back on my mac, and immedietly the "finder" window pops up (which never happens.) i open up safari and it ALL my bookmarks are gone. also, a box keeps popping up every ten minutes or so that says that all my keychains have been lost, and i have to enter the password i enter when i startup my mac for internet to work. that's my problem w/ safari.
now, with itunes, it says that it can't load my normal library, that it has to open a damaged one. but ALL MY SONGS ARE GONE. limewire might have something to do with this, but at least i still have all my songs on there.
also, my iphoto pictures are ALL gone except for about 5.
oh, and about ichat. everytime i log onto it, it's as if i have just first turned on my macbook. like it goes through the directions on how to use it, asks me if i want to use jabber, bonjour, teaches me about video chatting, etc. i dont know WHY the heck it does this. but i'm afraid. i don't wanna make a fool of myself at the "genius" bar and wait forever at the store or on the phone with one of the mac guys. so someone, please.. help. or if this has happened to you before at least console me.

Welcome to Mac-Forums, loseyrself.

Did you manually change the name of your user account?

the only thing i could think of is when you had your macbook plugged in for all that time it might have overheated resetting or screwing up your computer..but you should go to the genius bar and see what they say

Can you still get at all your stuff through the Finder? It sounds like your account has somehow being damaged, and OS X thinks you're a new user (so your library files for iPhoto and iTunes are damaged, put other programs still see your photos/music because the actual media files are still in the same location).

It might be worth speaking to a Genius and see what they recommend; it might be a hardware issue.


PS. If you've changed the shortname on your user account, I think that could very easily cause something like this to happen.