Which version did you have before ? Do you remember ?
Did you uninstall the previous version before installing this one ?
Right after the problem, without restarting any process (Thunderbird for instance) and if possible without disconnecting your mobile, is it possible to send me the log files to support@birdiesync.com ?
On the desktop in C:\Program Files\BirdieSync\log: DesktopProvider.log and ThunderbirdService.log
On the device in \Program Files\BirdieSync: DeviceProvider.log and BirdieWatcher.log
In C:\Documents and Settings\<user name>\Local Settings\Temp\ : WCESMgr.log
Regarding the problem of icons, I think it's because of some changes in BirdieSync icon management between the two different versions you installed. Normally, icons should be correct in ActiveSync options window. But your ActiveSync partnership very likely kept the old icon settings. If you delete and recreate your partnership, your icon problem will very likely be solved.
As for the "unresolved items" problem, I will need the log files in order to investigate it.
I've exactly the same problem. I've a Smartphone HTC S710 running Windows Mobile 6.0. But the problem occurs only when I create an appointment on the smartphone. Appointments created on the PC will sync without problems.
From what I see in the logs, I think there is a problem writing a particular event on the mobile (transfered from the desktop). Could you send DeviceProvider.log (in \Program Files\BirdieSync on the mobile) to support(at) birdisync.com ?
Thanks.