Compaq dc5800 - Microtower PC Reference Manual page 227

Table E-10 Solving Mouse Problems (continued)
Mouse does not respond to movement or is too slow.
Cause
Mouse may need cleaning.
Mouse may need repair.
Computer is in standby mode.
Mouse will only move vertically, horizontally, or movement is jerky.
Cause
Mouse roller ball or the rotating encoder shafts that make
contact with the ball are dirty.
Solution
Remove the roller ball cover on the mouse and clean the
internal components.
See the Worldwide Limited Warranty for terms and conditions.
Press the power button to resume from standby mode.
CAUTION: When attempting to resume from standby mode,
do not hold down the power button for more than four seconds.
Otherwise, the computer will shut down and you will lose any
unsaved data.
Solution
Remove roller ball cover from the bottom of the mouse and
clean the internal components with a mouse cleaning kit
available from most computer stores.
Solving Keyboard and Mouse Problems 219