Continuous System Shutdowns (Macbook)

I tried looking around the forums but it seemed like I couldn't really find a thread that totally addressed my problem so I apologize if I've missed the thread somewhere.

Awhile ago, my macbook started to shutdown by itself. The message that pops up right before it does is the same message you'd get if you pressed the power button while logged on(Are you sure you want to shut down your computer now?). Usually, it won't pop up or become an issue if I am actively browsing/using the computer. It's if after a period I don't touch the keyboard or trackpad that the message will pop up. Before, if I set something on a key (fn, command, shift etc.) heavy enough to press it down I wouldn't get the notification but after a period of time, each subsequent key would stop having the effect of stopping the popup.

I have tried adjusting my Energy Saver settings but to no avail. I saw some people suggest to others with problems to look at the macbook's crash logs but I don't have any listed that seem to be recent if I am looking in the right location (more about this mac, software: logs) The problem started after a little drop of water went on the keyboard but it fell in a way that I could wipe it off fairly easily(which has happened before and everything has worked fine) without worrying that it totally seeped into the space between the keys. However the people that I have spoken with about that say that they think it's unlikely that that small of a drop could have caused any water damage. Any suggestions? I'm really not that computer savvy so any tips would help.

Try this:

Intel-based Macs: Resetting the System Management Controller (SMC)

Thank you! However, if I've done it right (disconnect charger then batt. then pressing down power button for 5 sec.), it doesn't seemed to have fixed the problem. Earlier it had been shutting down fairly quickly after the message popped up asking if I wanted to shutdown but now the popup seems to remain on the screen for a longer time so I have longer to respond and hit cancel (though the timing on how long the message stays up before shutdown as well as how long after inactivity it takes to appear has always been sort of random since the issue started).

Some things I forgot to mention (though I have no idea if they are relevant): Occasionally after a shutdown, when I reboot, the desktop changes back to default instead of the picture folder I selected before. If I go to change it again, I have to repick the folder since it disappears from the desktop options. I am also on Mac OS X (v. 10.5.8). It is the 13-inch but from the 2009 period so I'm not sure if the random shutdown issues from earlier versions apply?

did you already find a solution? Having the same type of problem, including the drop of water.

Cheers

Hey sorry it took so long. In the end I'm not sure what the problem is for sure, but it stopped shutting down when I took out the battery. I think the battery was swelling and pressing on something, but when I took it out and used it just with an outlet the problem stopped for me.