The central site has a 5.5 Exchange Server (SP4) running on a BDC named CORP (NT 4.0 with SP6a and Post6a security Rollup).
The remote sites (Dallas, Austin, and San Antonio) are all connected via a WAN using Netscreen 10's and 5's and VPN tunnels. Each of the remote sites has an NT4.0 server with WINS doing a push-pull replication with CORP which is also running WINS.
This configuration has been in place for at least 3 years and the remote workstations used to be Windows 98. Over time, many of them have been upgraded to Windows XP Professional. Outlook 2000 has always been used as the client and we were not aware of any major problems until about 6 weeks ago. Note: the private information store on the EXCHANGE server has grown to about 7GB over the years.
On a random but pretty frequent basis, users are going into OUTLOOK 2000 client at a remote site. The OUTLOOK screen loads but never completes (the number of messages in the inbox does not display). The hour glass stays until the user brings up task manager and kills OUTLOOK. Here's the interesting part. The user is unable to open his/hermailbox until we (the tech support people) do the following: at the 'local' site in Houston, we open OUTLOOK 2000 client, go into their mailbox, and sort their mail messages (usually by subject and then back to date received - but it really doesn't matter as long as we change something.). After this, the user at the remote site is able to successfully open their mailbox. Also, even if the mailbox opens, there will be some emails with attachments (usually larger attachments 100K+) that will not open - goes into the "Not Responding" stall.
So, is this a RPC over TCP/IP problem, a corrupted views problem, a router config problem ? Any insights greatly appreciated. PS: Yes I know that Server 2003 with Exchange 2003 and RPC via HTTPS is great, but my config will not support this right now. (Still have plenty of 98 PC's not to mention no AD or Exchange 2003).