Subject: Error updating local ID file: Cannot write or create file (File or disk is read only)
If these are windows users, can you verify if there any local restrictions to write to disk or folders such as c:\program files\lotus\notes\data … give full admin rights on local PC to one of them as a test and see how it goes …
Workaround could be to use a back-up copy of the newly certified id file but this could be cumbersome depending upon how many users you got …