Credit goes to [NFC]Wave for bringing this long standing issue to my attention and for many hours attempting to come up with a decent solution.
Are you a Mozilla Thunderbird user who lives in an area that observes Daylight Savings Time? Is your computer running a Windows operating system with FAT or FAT32 formatted drives? If so, chances are you may have experienced problems with Thunderbird since the change from Daylight Savings Time went in to effect earlier this month. A long standing bug that causes severe performance issues and has existed in various stages of the Mozilla project now known as Thunderbird continues to plague users despite having a history of bug reports that have been filed via Bugzilla, Mozilla"s online bug reporting tool.
Users experiencing this bug state that when they initially open Thunderbird, their Inbox shows nothing, staying blank as the application says that it is checking for new e-mail messages. Users closing the application and re-opening it find that it displays the status as "Rebuilding", eventually reloading, but taking 2 minutes or more to do so. They also report that whenever Thunderbird is open their computer becomes very sluggish and unresponsive.
Several users have reported that compacting their folders and removing all old messages from their Inbox may provide a solution to these symptoms, while still others have reported having to delete corrupted .msf files from their Thunderbird profile, then re-open Thunderbird and perform the compact routine. While these options may provide relief for frustrated users, they hardly qualify as a solution to the problem.