Just try to connect my old Pocket PC (HP iPAQ rx3417) to the laptop using Microsoft ActiveSync 4.5, but pop up an error message:
Cannot verify the version of ActiveSync on your device. A program such as a firewall may be blocking a port ActiveSync uses to connect to the device, or you may need to upgrade to a more recent version of ActiveSync on the PC.
So, I turn off PCTools Firewall Pro, and restart, but still have the same error. So I try to reinstall ActiveSync with older version, 4.1, hope that the problem will be solved. But the problem still there, with a different message:
This version of Microsoft ActiveSync is not compatible with the mobile device. Please upgrade to the latest verison of ActiveSync and reconnect.
I think the problem might be caused by Nokia PC Suite, so I uninstall all the Nokia related software and driver. I also uninstall PCTools Firewall Pro, and restart the laptop several times. However, the problem is still not solved.
Finally, I install Microsoft ActiveSync 3.71, and the problem is solved. Even I install PCTools Firewall Pro and Nokia PC Suite again, there is no problem for the connection of the Pocket PC with the laptop.
And, I suspect that this problem is caused by Windows XP Service Pack 3.
You can download older version of MS ActiveSync from here.