Hardware problems, CD/floppy/sound

Can anyone help with this problem please. Windows XP
Home Edition.

My CD drive misbehaves; on audio CD playback it either
gives clicking noises or stops on tracks for a few
seconds, or worse still it just locks the entire system
up and I have to re-boot out
Similar happens on DVD play - same drive
I get distortions on sound effects as well but it does
not seem to be a sound card problem as an external sound
source just played into the external socket plays
normally (including same CD's as cause problems on CD
drive)

I replaced the CD R/W/DVS drive with a brand new CDR/W
drive but got same problems and have replaced original
drive#

My A-drive (floppy) misbehaves - giving Error 20
messages, failing to write, and generating messages that
the drive door is open. Again I replaced the drive with a
new one but get same results (though have kept new drive
in)

I get image distortion on colour scans through a USB
connected multipurpose HP unit.

Yet the rest of the system works OK, printing, ZIP-drive,
hard drive, etc.

I have unloaded all software and then reloaded Product by
Product, taking restore points along the way but cannot
seem to clear the problem.

If anyone recognises these symptoms and can diagnose a
cure I would be grateful.