dovecot - Jun 2010 - Problem after migrating from mbox to maildir and squirrelmail

Hi all, 

I just finished migrating from mbox to maildir (and upgrade squirrelmail to the
latest version) with some issue. We are using Postfix 2.3, Dovecot 1.2.7 and
Squirrelmail 1.4.2.

One of user report that suddenly all his Sent and Drafts emails were disapeared.
After log in to webmail, I found out that there are 3 new folder called Drafts,
Sent and Trash apart from Drafts,Sent,Trash underneath INBOX folder, and all his
sent and draft emails were there. I thought I just move the email from Sent
folder to the Sent underneath INBOX, but I was wrong. Now he got all sent emails
in Sent items but after refreshed the webmail, INBOX wont open at all. it just
blank but in the left side it said the amount of his email.
what did i do wrong? is it something to do with the dovecot.index and
index.cache or the uidlist?

please enlighten me....

thank you

Hendry