If you have a blinking message waiting light but no message try pressing *58 then your extension and the blinking should go away. If that doesn’t work then try rebooting your phone, which seems to do the trick.
To reboot your phone: Unplug the cable on the back of your phone and plug it back in. The phone will reboot and the blinking should go away. Please let me know if you have any further problems with this.