When I go to "Build Checks" in Solidworks I get an error message when the Design Checker window opens stating, "This action cannot be complet becasue the other program is busy. Choose "Switch To" to activate the busy program and correct the problem"

I've tried restarting and numorous other things to try and fix this but no luck. Does this program rely on another program to run? I occasionally get this message when using design tables but starting excel before doing so usually fixes this problem.

Thanks in advance - Craig