JDK1.4.1
Netbeans Q-build 200202190100
SDI mode
Unpredictable, random but very frequent, extremely
annoying.

I have been using NetBeans for over 2 years and I
cannot remember that I had a version that did not
have this bug.

I can't at this stage make a testcase to show it
because I don't know the conditions.

So I try to describe what happens:

When stepping through GUI code, suddenly the green
highlight disappears.
When pressing F8 again, still the same but the
system beeps as many times as I press the key.

I can bring the debugger back to life with any of
these methods:
1) on the debugger console, I click on the last link.
2) Menu|Debug|Pause, then F8 again

In a variation of this scenario, focus is
transferred to another source file, most of the
time showing the caller.
Again, 1) and 2) brings the debugger back on track.