2 Ways from what i have gathered.
1. Try this. Go to control Panel>Add remove programs>Windows Setup tab
Take the Check out of Accessibility. Press Apply ok to remove it.
Reboot.
IF you want to reinstall accessibility, go back to control panel>add remove programs>windows setup and recheck it. Apply, OK
2.Another way to fix it, if you can't start the computer is to start using a boot disk. Edit the the c:\windows\system.ini file. using edit.com to exclude the line that refers to that file. You can do this safely by adding a semicolon at the beginning of the line.
To open the edit.com if it is not on you boot disk use this command from the c:\ prompt
"c:\windows\command\edit c:\windows\system.ini"