A strange (and old) problem with urxvt

[Rafał Mużyło]

I don't remember, when this problem occured for the first time. It's
probably been over an year. The catch is this seems to happen completely
randomly.

Sometimes, for no apparent reason, urxvt first stops accepting input and
then stops being redrawn. When this happens, I have to kill urxvt. Now
comes the funny part. Sometimes, when I try to start a new urxvt too
fast after last one was killed, I'm unable to - meaning process starts,
but no new window appears. To make things even more interesting, if at
that time I try to start xterm, it acts same way.

The main problem with this problem is that I can't reproduce it at will.
Any thoughts ?