This is a bug in all versions of 4.2.1 OS. The only way to get rid of it is to downgrade the OS to 4.2.0. It's a simple process. TMobile doesn't offer the old OS's anymore. However, there are other carriers that do. Simply find one that still offers a 4.2.0 version and load that one. I recommend the 126.96.36.199 as it was a very stable OS.
Here's where to find the OS's. Just search through the GSM carriers for the 8100 Smartphone OS. BlackBerry Operating System Downloads - BlackBerryFAQ
When you find the one you want, here's what to do:
1. Download and install Desktop Manager to the PC if it isn't already.
2. Download and install desired handheld OS software from the above link.
3. Delete the file called vendor.xml located in c:\program files\common files\research in motion\apploader
4. Plug in BB, run Desktop Manager. Then open Application Loader and you should be prompted to downgrade.