Add a resource mailbox to a meeting locks Outlook 2010 for up to 30 seconds

Hi all,

We have Outlook 2010, Exchange 2010 has both my mailbox and the meeting room's mailbox on the same server but different database. We have Exchange 2003 with the majority of users on (nearly 1100). About 10 users and this one resource mailbox are on the new server config. We use a CAS array with 2 servers and a DAG with 2 servers.

When you create a new meeting, put the meeting room in the TO: box and press send, the Outlook client can lock up for up to 30 seconds. This does not happen if I do it from an Outlook 2003 user who is on Exchange 2003.

I turned on Outlook logging and found that the free/busy information does not cause an issue.

Outlook web access also does not get an issue when using an Exchange 2010 user.

I tried moving it to the same mailbox database as me, that did not work.

Any ideas???