My mouse (Touchpad) has been unresponsive on my Thinkpad T440p for a few hours now. Updating the driver, rebooting the machine, nothing worked. I am on Windows 10.
The Realtek HD Audio Driver seems to be responsible for this!
I uninstalled the Realtek HD Audio from Add/Remove Programs & rebooted the machine & the mouse started working fine. However, after a few minutes, the same problem recurred again. I went to Add/Remove Programs and saw that Realtek HD Audio had reappeared.
This is because Windows 10 updates drivers automatically. To disable this
Go to Control Panel->System->Advanced System Settings Hardware Tab->Device Installation Settings
Choose "No" in the option to automatically download drivers.
I then uninstalled Realtek HD Audio again. Uninstalled Realtek LAN Driver also just to be safe. Went to c:\program files & deleted the Realtek directory. Went to c:\program files (x86) and deleted the Realtek directory there also.
Touchpad is working fine now. Keeping fingers crossed.