OK here's the problem:
I was working with 2 Linux computers with only 1 VGA monitor and 1 keyboard. So I had to plug the monitor back and forth between the 2 machines.

Now usually the monitor displays fine, but after a couple of switches, one of the computers will no longer show the command line where you can type in input. However, everything else displays correctly and you can still type stuff into the command line and it'll register properly. Just that whatever you type "lags" in the sense that you have to press ENTER repeatedly to get the screen shifting upwards to see what you just typed.

What I tried:
1) shutting off and turning on monitor
2) moving the vertical position ALL the way up
3) unplugging the VGA cable from the monitor and computer and replugging it back in
4) logging out then logging back in

Results:
NONE of these worked. Same problem exists.

I know I can restart the computer and it'll work, but was wishing for a more elegant solution. So Linux experts, any ideas?

My best guess would be

- the keyboard port is now flaky from constant activity

or

- the keyboard itself is on the way out.

Options

- If USB test a different port. : Sounds more like the port since it is one machine that is flaky. If this is a PS2 connector you are just out of luck since the only option would be to replace the board. However if the port is flaky but has life left you could -->


- purchase a a/b switch : Cheap one is about $10 : This way you will preserve whatever life is left on the ports / keyboard.