Keep on getting "backend failed" messages.

[Kyle Schmitt]

I'm running a number of cups servers at different locations throughout the company, and certain printers keep on stopping every few days with messages like,

cups backend failed

When I click start, or cupsenable the printer, it works fine for awhile again.  It only happens on a few printers (out of literally a hundred), but on this it happens repeatedly.

Any idea what may be causing it, or how to get cups to recover on it's own?

If it matters, I'm running:
CentOS 5.1 64 bit
and it's stock CUPS
1.2.4

Thanks,
         Kyle