Yup, sounds like a dodgy harddrive. I mean, the hard drive is the one thing that moves the most (apart from the fans of course) in a computer as the head writes and reads the data on the hard drives. It also means that if you drop a laptop, the hard drive is usually the first thing to go. In case you dropped it, I mean

.
Hang on, you left your Notebook running for 2 weeks? Jeez, your battery must be completely messed up, the zero-point must have been completely lost so that the battery can't charge up as much as is normal because it's had power through it for a sustained period of time. So your battery won't be able to supply as much power as usual to the machine and the components. It's less of a problem with normal tower PCs where the power comes through the mains supply, the only issue is individual components overheating.
So first on the shopping list is a new compatible battery for your laptop, then if that doesn't fix the problem (should be the fix though) then try a new hard drive.
This post was brought to you today with the following lesson:
Keep your laptop powered down when you're not using it!
PS. Just out of interest, why on Earth did you leave your laptop computer on for all that time? Catch up on some P2P/Bittorrent while you were away or something?