EDIT: Fixed link
Download 3.8 OS install file http://www.t-mobileapps.com/download..._3_8_0_128.exe
Go To Control Panel – Add/Remove Programs - Uninstall Desktop Manager 4.0
Go To Start - Search for vendor.xml file and delete
Run 3.8 OS install (downloaded from step 1)
Allow it to downgrade all 7100 applications (including apps like breakbreaker, browser, etc)
Allow software to Backup your data from your 7100 to your PC. On the last step of the OS install it will try to restore backup files and will HANG –
Unplug and plug-in the 7100 on the USB connection to get it to exit the program.
Reinstall Desktop Manager 4.0 and Run program
(Downgraded version of 7100 should sync with software, if it doesn’t repeat steps 2 and 7)
Select “Backup and Restore” icon – Now select Restore – choose backup file (created to backup data in step 6). now CANCEL restore operation
(if you don’ t cancel in time it will lockup on Bluetooth options, repeat steps 2 and 7).
Select Advanced (The data file will already be loaded) – In the Left Frame Select “Bluetooth Options” and Delete it. Now Save/Exit the advanced menu.
Select Restore (again) – this time run the restore function. It should upload all your data to your 7100 without hanging.
It may take up an hour for your internet and phone to be fully operational (after about 90 minutes and a few hard reboots I was up and running).
The 7100 will run and sound better than ever, but BES users will lose wireless sync function as 3.8 does not support that feature.
Please let me know if any clarification is needed on these instructions.