Please have a look at this:

http://www.cisco.com/en/US/partner/docs/wireless/bridge/1400/release/notes/p311jarn.html#wp17024

I know it relates to 1400 bridges and you are using 1231, but maybe the bug mentioned - CSCsd91189 - relates to both?

I tried to look at this using the bug toolkit and it says bug CSCsd91189 is superseded by bug CSCse78527. I then tried looking this bug up and got the follwoing message:

Information contained within bug ID CSCse78527 is only available to Cisco employees. It is our policy to make all externally-facing bugs available in Bug Toolkit so the system administrators have been automatically alerted to the problem. By choosing to save this bug, you may be notified when the decision to make this bug available to you has been made. Note: Some product enhancement requests and documentation error bugs may not be available in Bug Toolkit.

Never known a bug be 'hidden' from the public before? Maybe you could get in touch with the Cisco tac to find out more details about htis bug to see if it is related to your probelm, and if so what workarounds or solutions you can implement.

Strange!

Good luck

Darren