I had a very similar problem and this program was the only one that worked.
Before starting the steps below place your XDA in the cradle and wait for it to sync.
1. Install attached software
2. Run MobileVault from 'Start > Programs > MobileVault > MobileVault'
3. Click on the'File' menu and then 'Open'
4. Browse to 'My documents' and select 'backup1.stg'
5. Once file has opened click on '+' next to the small computer icon in the left hand panel
6. Click on 'WinCE Databases' folder
7. Right click on the 'Appointments Database' in the right hand panel and select 'Restore to Desktop'. This will pop-up a window, select the desktop and then click 'Ok'
8. Repeat step 7 for the 'Contacts Database'
9. On your desktop a new folder will have been created called 'WinCE Databases'. There will be two files - send these both to me.
10. Repeat steps 7-8, but this time select 'Restore to Mobile Device'. In theory this should restore them to your pda.
If step 10 doesn't work, then;
11. Remove the xda from the cradle
12. On the xda, click on the start menu and select 'ActiveSync' (if its not in the menu it will be in the programs option)
13. Select the 'tools' menu at the bottom of the screen and then select 'Options...'
14. Click on the 'Options...' button, and untick the 'Enable PC sync using...' option beneth the 'When cradled' text.
15. Click on the 'Ok' to the top right of the screen, and then repear for the next screen, finish by clicking on the 'X'
16. Now place the XDA back in the cradle - it shouldn't sync now.
17. Repeat step 10, and see it it works. Fingers crossed!!