If Click to dial works OK (you can right click on a contact and call one of their contact numbers) but when a call comes in; a Call summary window does not pop up on your computer, this is often because the Firewall or Anti Virus software on your own PC (or maybe a network firewall) is blocking the traffic from the phone to the PC.
Please check your Firewall configuration to see if it is allowing traffic for Flexor Manager (on TCP Port 4052 if required) to reach your PC from your phone. Further information including instructions for a connectivity test is available here.
In Microsoft XP, Windows Firewall this is enabled by Adding a Program on the Exceptions Tab. You can get to the Windows Firewall Settings via the Security Center in Windows Control Panel.
It has also been reported that exiting Flexor and exiting the Anti Virus and or Firewall software and then restarting Flexor, then restarting the security software can resolve the issue.