Note: This problem should only be present with BirdieSync version prior to 18.104.22.168. Since this version, a workaround was found to avoid the Windows Mobile 5.0 bug.
During installation, upgrading or uninstallation of BirdieSync on Windows mobile 5.0, you may have a cryptic error message mentioning that you simply cannot install or suppress BirdieSync on your mobile without any explanation... :(
Unfortunately, it is very likely that the problem doesn't come from BirdieSync but is caused by a bug of the Windows mobile 5.0 installer. Without giving all the details, the installer needs too much memory, that would cause it to abort the uninstallation. This problem affects all the applications, not only BirdieSync.
The best workaround is simply to soft reset your mobile and as soon as it rebooted (don't loose time) to manually uninstall the previous BirdieSync version manually (on the mobile, Settings, Suppress Programs) and then to install the new version.
Caution: If you ever had the error message mentioning that BirdieSync could not be uninstalled, don't accept to remove it from the installation list since you wouldn't be able to remove it any longer.