SPR 501024 exists for this situation. It is open as high priority but unless a SW member of staff can dig a little deeper into its conditions I cannot see the specific circumstances it has been known to happen (i.e. SW versions, Windows OS)
Does the user on that machine have the PDM Client add-in turned on? If so, turn it of on both the left and right side of the Add-ins window.
When the SolidWorks PDM (standard or pro) add-in turned on, then the collaboration settings are turned off when SolidWorks launches.