While you say you are using a MacBook Pro running Mac OS X 10.6.8, it’s unclear what model you are using. Please update your answer with the exact model number so we have more info to work off of.
That said, have you tried hooking up an external keyboard & mouse to the USB port on the machine to see what is happening? If an external keyboard and mouse work, but the built in keyboard & trackpad choke it could mean there is an underlying hardware issue.
But don’t panic!
If it cleared up with rebooting it might simply be an issue with your PRAM or NVRAM depending on the make/model of your MacBook Pro.
Instructions for dealing with the PRAM are here on Apple’s site; ignore the title that refers to Mavericks since those instructions should work with all version of Mac OS X:
- Shutdown your Mac.
- Start your Mac.
- Immediately hold down the command + option + p + r keys.
- You will hear the Mac OS star up chime once, and then once more as it restarts form the PRAM being reset. After the second “BONG” sound let go of the keys & boot up as normal.
Instructions on how to reset the NVRAM are here. It seems a tad more daunting but not really that hard to do:
- Shutdown your Mac.
- Start your Mac.
- During starup hold down the command + option + o + f keys.
- When you get into open firmware—which should look like a terminal prompt—type in the following two commands:
reset-nvram return
reset-all return
Your MacBook Pro will now restart with cleared NVRAM settings.
Now if none of that worked—or the key combos above were ignored—it points to a hardware issue with the keyboard itself. Could be something as simple as the ribbon cable being loose or just a damaged keyboard. Next steps all depend on what was successful—or not successful—after following these basic steps.