You did say any assistance didn't you? I have the same problem sometimes, when it happens I use the page up/page down keys one or twice then go back to using the scroll keys. My theory is the commands go into a ring register which clocks around with each command and if after a predetermined amount of commands the command is the same as the first command in the register (which has been clocked back to the start) the computer thinks it has a stuck key and disables.
Just a theory though...