Ok, let's see a show of hands - how many people have GemStone projects running on 6.1.5? Ok, of those, how many encountered a mysterious crash yesterday?
It seems that RcQueue uses a timestamp for its records. That timestamp is the number of seconds since January 1, 1995. It's constrained to be a small integer. Yesterday, it overflowed to a large integer, violated the constraint, and brought our production server to its knees.
Fortunately, there's a fix in GemStone 6.6 - it now records timestamps since January 1, 2005. There, that fixes the problems. Everybody set your watches for January 5, 2022.