You hit it right on the head, Rip.
With the Nav program we make, I'm the guy with 4 systems (Windows 2000, Windows XP Pro, Windows 98, Windows NT 4) who tries to duplicate and hunt down the error messages customers report. Its a lotta work and when you do find the critter, its largely a thankless job ("You should've found it in the first place before releasing").
Bugs, err, "undocumented features" happen. Its one thing when a program is in beta under 10 or so systems. But release it to a few thousand and then that's when it gets interesting!