Exchange 5.5 MTA Major problem

Update: After a few reboots, disabling and re-enabling my AV software, and doing any little troubleshooting here and there I could think of; Exchange 5.5 is finally processing mail in the MTADATA Folder.  At last reboot I had 100MB of free disk space due to this issue.  I am now at almost 1GB of freespace, so I'm about 1/3 of the way back to normal.  The MTA seems to be processing mail now but slowly.  I'm afriad that when I re-enable mail flow from external incoming messages back to this server, we will run into the same issue again.  Seems that the issue was really only for internal mail, as I just sent a test from telnet through the failing server and received it very quickly at my mailbox on an Exchange 2003 server.  So the thousands of messages queued in the MTADATA folder are for internal mail?  How can that be?  Outgoing and incoming over SMTP seem to be ok, just need to make sure the MTA folder doesn't consume more disk space than it has available.  Its currently only on a 9GB partition, which should be enough, does anyone have any idea what would cause the MTA to generate so much internal activity?

I am going to recommend at this point, that we move remaining mailboxes on this box to one of the other Exchange 5.5 boxes, move public folders, etc, to another box as well.  We could also install a new IMC on one of the other Exchange 5.5 boxes and route all outgoing mail to one of the Exchange 2003 machines or directly to the internet.  We are urgently trying to migrate away from Exchange 5.5 as quickly as we can.  

Any tips on this process.  Especially for the following:

1. Remove IMC on failing Exchange 5.5 server
2. Install new IMC on either a different Exchange 5.5 machine or on one of the Exchange 2003 machines

Thanks
Joe

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Hi!
I would suggest starting with reapplying SP4 for Exchange 5.5. There is a chance that this will fix your problem.
Here are examples (screencasts) of moving/restoring exchange 5.5 services to a different machine:
http://www.netometer.net/video/tutorials/move55/index.html

http://www.netometer.net/video/tutorials/replace55/index.html

http://www.netometer.net/video/tutorials/restore55/index.html

Dean

UPDATE: The problem was not with the MTA itself, but rather a disk space issue.  Just before I experienced this problem, I had enabled a replica of one of the public folders on the server in question, to replicate to another server, running Exchange 2003.  Since Exchange 5.5 uses the X.400 connector over the MTA to transfer messages, even public folder replication, Exchange 5.5 had dumped thousands of files into the MTADATA folder.  Rather than stream the information real time to the new replica server, Exchange 5.5 dumped copies of each message into the MTA for transfer to Exchange 2003.  Since I only have 2GB or so of free space on this partition, and was transferring over 4GB of public folder data, needless to say this caused an issue.  Fortunately, at one point, we reached a critical point, Exchange 5.5 had sent enough public folder data so it would now leave 100MB free on the partition the MTA is on.  From there on, the free space started to increase, as Exchange 5.5 delivered the public folder data to exchange 2003.  The problem worked itself out and both systems are working normally.  I now know not to replicate public folders larger than a few GB from this server to another server without keeping a close eye on the MTA partition free space.  Whew!!!