I have discovered that my problem is narrowed down to the internal parallel port cable in my award P1 PC. Basically, the motherboard delivers the port as two rows of pins (more like a bunch of 2-pin jumpers connected together side-by-side). I have a cable which converts this into a parallel port connection. It seems that this cable could be the culprit, because I tested one connection on it (I think parallel pin 22), and it is open.

Is it always safe to connect pins 18-25 to ground, even if I have a printer attached? or are these pins used by some manufacturers for other purposes? If it is safe, I'm tempted to directly solder those 7 pins on my motherboard together.

If that's one of the ground pins?, and it sounds like it is, then it won't make any difference - they are all simply connected together anyway.

You've blown the chip, you need a new motherboard!.