I RECENTLY had a new motherboard (Sempron 2800) installed , replacing FIC P4m Pentium in a Tiny package. I now find that the mouse (PS/2 ?) STAYS on when the pc is turned off. The installer doesnt seem to know quite what the cause is, but assures me that it will be ok to leave it as it is. The mouse works perfectly well, but it bothers me that it is not quite right.
Any suggestions?  I have 2 computers that keep the mouse light on, I've never worried about it, but now you have me interested so I'll check it out.At least on some newer systems/mbs, PS/2 ports are powered while the computer is off.  This is intentional to allow keyboards with power keys to turn on your system.  
For some, even a USB mouse adapted for PS/2 will stay lit.
Remove power to the PC (uplug it or turn off the power strip) if you don't like the setup.

Dell
Or someone else may answer it for us.
Thanks Dell.  Thanks for the replies - all seems to be well so I'll just ignore.
I did wonder because the pc switched itself on a COUPLE of TIMES soon after I got it - fixed with the HELP of the service line, and I thought that maybe it was a similar occurrance.