Some users of early production ThinkPad X220 systems might notice erratic or jumpy touchpad functionality when the system is plugged in and powered by the slim 90w AC adapter. This symptom is not evident on all systems, and is not evident when running on battery or using a different AC adapter like the standard 65W adapter, or a standard 90W adapter option or from other model ThinkPads.
Later production X220 models incorporated updated the Touchpad firmware and will not exhibit these symptoms.
If you have experienced these symptoms and wish to update the firmware, you can flash the Touchpad firmware by downloading the x220 touchpad.rar file attached at the bottom of this KB. Unpack the rar to find three files:
1) Word doc with instructions which are listed in this KB
2) The PR1063847-tm1611.img file - this is the actual firmware code
3) The synpaticsReflash executable file
This reflash process is unlike a normal driver update and will take 15 to 20 minutes, so please only apply it if you are sure you have the symptoms and have the time available to allow the process to complete. Do not power off the system until the process completes.
Updating the firmware
Step 1) After unpacking the rar file, launch the synapticsrelash executable file and select the Touchpad device.
Step 2 - Select the PR1063847-tm1611.img from your hard drive
Step 3 - Select Open
Step 4 - Select Yes to update the firmware
I have this same jumpy touchpad issue, and it's driving me insane. I just downloaded the firmware update mentioned in this thread, but the installer isn't working. It runs but the button to select an image file is greyed out and so I can't actually apply the patch.
Any help would be much appreciated... I'm at my wits end here! 
