HP Compaq dx2450 MT Reference Manual page 92

Computer will not respond to USB keyboard or mouse.
Cause
Keyboard or mouse is not connected to computer.
Computer is in standby mode.
Computer date and time display is incorrect.
Cause
RTC (real-time clock) battery may need to be replaced.
NOTE: Connecting the computer to a live AC outlet prolongs
the life of the RTC battery.
Cursor will not move using the arrow keys on the keypad.
Cause
The Num Lock
Poor performance is experienced.
Cause
Processor is hot.
Hard drive is full.
Low on memory.
Hard drive fragmented.
Program previously accessed did not release reserved
memory back to the system.
Virus resident on the hard drive.
86 Appendix C Troubleshooting
key may be on.
Solution
Connect keyboard and mouse cables to computer.
To resume from standby mode, press the power button or
press any key.
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
First, reset the date and time under Control Panel (Computer
Setup can also be used to update the RTC date and time). If
the problem persists, replace the RTC battery. See the
Hardware Reference Guide for instructions on installing a new
battery, or contact an authorized dealer or reseller for RTC
battery replacement.
Solution
Press the Num Lock key. The Num Lock light should not be on
if you want to use the arrow
disabled (or enabled) in Computer Setup.
Solution
1. Make sure airflow to the computer is not blocked. Leave
a 10.2-cm (4-inch) clearance on all vented sides of the
computer and above the monitor to permit the required
airflow.
2. Make sure fans are connected and working properly
(some fans only operate when needed).
3. Make sure the processor heatsink is installed properly.
Transfer data from the hard drive to create more space on the
hard drive.
Add more memory.
Defragment hard drive.
Restart the computer.
Run virus protection program.
keys. The Num Lock key can be