Broken iCal Connections for me

[claud1e]

Hello-

I just upgraded from 5.0.16 RedHat 64bit to 5.0.18 RedHat 64bit and ever since users using Sunbird to connect via iCal url can no longer edit any meetings.

Cannot dismiss meeting reminders, cannot create new meetings, cannot edit current meetings, etc.

Error message only says:
An error occurred when writing to the calendar My Calendar!
Error Number: MODIFICATION_FAILED
Description:
(nothing)

Has anybody noticed this behavior?

Thanks in advance,
Chad