error 8921.245

I have tried everything you have suggested on your sites, but my computer is still giving me error 8921,245.  Everytime I try to run a live update it says live update already in progess, and thats it.  I have even tried uninstalling NAV 2011 to reinstall, but it would not let me unistall it.  I have only had your program for a few weeks, and getting tired of how it is not working correctly.  Please help.