Feedback has been coming in rom the multiple local user community. See my thread "Dismayed...":
Multiconsole X is growing more popular by the month.
Many others have brough the problem up on other forums as well. Crashes on multiple X servers with Nvidia cards is a known given in the community.
Any of you out there running multiple local servers on your machines and suffering from crashes are invited to join in requesting that Nvidia address themselves to the matter.
Currently, Nvidia has no debugging mechanism. The Nvidia bug report script logs only for the first X server alone. Additional servers, on which the crashes usually occur, are ignored.
Many have reported this problem with Nvidia cards, running on a gamut of kernel and driver releases. In spirit of the season, let us make it clear that we are very appreciative of Nvidia's efforts accross the board and of their valuable boost to the Linux community at large.
Hoping and wishing...