I just got the same problem. Track pad and key board lockup after software update on 10/9/2011. Firmware was updated and notes in firmware update referred to keyboard issues. I should not have ran the update as I had no issues but I trusted the updates from Apple. Now I do have an issue and have update remorse.
Macbook OSX version 10.6.8, 1.83 GHz, Intel Core 2 Duo, Memory 1GB, 667MHz, DDR2, 160GB HD
I now notice that the track pad will work after I removed the battery and replaced. But when I open Mail it locks up. Trackpad and keyboard are fine so far on all programs but when I open mail, immediately it locks up.
Never did this until the firmware update yesterday.
UPDATE: I just found this thread and it solves the problem. https://discussions.apple.com/message/16161031#16161031
MBP early 2008 here (purchased late fall 2008 as closeout)
Experienced the typical trackpad/keyboard issue and read through this and other threads. Just before my Applecare ran out last fall I had the Apple Store replace the Flex cable. All seemed to work well until recently when the problem returned.
I thought it was related to heat since it seemed to happen after the unit was in use for a while but now it can happen even a minute or so after waking from sleep or even on start.
I barely used this machine for the first couple years so the battery seems to be good. Here is the System Profiler readout:
Charge remaining (mAh): 5003
Fully charged: No
Full charge capacity (mAh): 5089
Cycle count: 37
Battery Installed: Yes
Amperage (mA): 287
Voltage (mV): 12579
Anything here that looks like it might be bad? I can't see anything wrong. I took it out and checked the cable but it also seems to be snug. Or could it be too snug?
Edit: OK, somehow this post was added on to the wrong thread...
I had a problem with my MacBook Pro 13" (2012) when the keyboard and trackpad stopped working for seemingly no apparent reason. When I consulted with Apple Care, they had me reset the PRAM, which did the trick for me. From what I understand, the PRAM is memory that the computer uses to keep basic display and input preferences and info, even when the computer's turned off.
Weeks ago I had installed a 3rd party mouse and keyboard. Even though I wasn't using them when the problem happened, Apple Care said maybe the software accidentally interfered.
To reset the PRAM, I restarted the computer, and when the apple screen came up and the chime happened, I pushed COMMAND+OPTION+P+R (four keys), and waited for it to re-chime a couple times. Then the keyboard & trackpad worked again! See the About NVRAM & PRAM page for details.
Might not be a cure-all, but it helped in my situation.