Here are some hardware problems that I've encountered recently and their solutions.
PC starts making a strange noise.
Mouse pointer sticking. Pointer will go up and down and to the right ok, but has trouble moving to the left.
Using a plug converter to plug a serial mouse into a PS/2 port causes the keyboard to fail and the mouse not to work. Removing the converter shows that the keyboard is still not working.
After installing a new network card Windows XP detected the card but came up with a "Data invalid" error and wouldn't install the drivers.
No sound coming from computer.