On 31 Dec 2011, at 20:20, THDW wrote:

[...]

> How do you go through your system to find out if there is something rogue which is causing the problem?
> 
> Is there an app that can help? 
[...]

Rebuilding all mailboxes will help:

Click on Inbox to select it.
Hold Shift and click on the last mailbox in the column.
This will select all the mailboxes in the column.
Then, from the Mailbox menu, apply the 'Rebuild' command.
This will rebuild all mailboxes and hopefully resolve the issue.

Hamid