The first time I syncornise my phone with Outlook it works nicely, but if I try and snyc it a second time without rebooting my PC it errors.

When syncronising my contacts it gives the following error in the log file:
Device contacts problem (unspecified error)
There was an error opening device Panasonic X800

When syncronising my calendar it gives a different error in a pop up window:
unable to open file:
C:\System\Data\Calendar

I don't want to have to restart my PC everytime I want to sync my phone with it. Does anybody have any ideas to fix this?