There are a couple of reasons you could be getting this BUG message.
1. Call Volume is set incorrectly for Symposium. Specifically Symposium Express. To fix this problem you need to change the settings under Call Routing>Global Ceiling from 30 to 90 and this should resolve THIS problem.
2. If this relates to 500 ports and conferencing, you need to get with Nortel and install patch MPLR08749, but this would be for an older switch. ca. 1998. Succession should have this fixed.
3. If you are getting this and it relates to an ACD set (You can determine this by the information after the BUG messaaging. It will give you a hex set of numbers. Either convert those in LD 32, or post them here and we can all take a crack at converting) you will need to call ETAS and have them unscrew your database, because this is would be a sign of Data Corruption.
4. ca. 2000 - MQUE prompt in the PLDN needs to be changed to 0, but if you have this issue, your switch would intermittenly INI during the day.
I hope this helps.
John