Sorry for the dalay, I "had" to go away on holiday!
I restored the database as per your instruction and now the ISPC admin login works ok but I still cannot download any emails from the pop boxes. Webmail works fine and mail is being delivered to the pop boxes and outgoing mail is being sent by smtp.
Just a thought, the original mail system was using Maildir but the new one is using Dovecot. Is there any difference in the config that might explain why the mail download won't work?