Even though I am usually the last one to jump on the
"don't re-invent the wheel" bandwagon, I feel that mikfire
is correct - a good bug reporting system can get very complex very fast.
At the very least, modify one of the existing ones heavily to
your particular uses. A nice one to use is bugzilla:
(it's number one in the list referenced above) It's almost free
(uses the MPL, an ugly cousin of the GPL) and definitely has had
lots of real-world testing. I also highly recommend GNATS, which
is GPLed.