Please Reactivate Error message

I have a user who started getting an error when he starts up his Draftsight.  The error reads "Please reactivate the product to continue using it" (see attached image).

I have read through many of the iQuestion posts concerning this issue (ie.https://swym.3ds.com/#community:70/iquestions:4773andhttps://swym.3ds.com/#community:70/iquestions:8983) and tried many of the suggestions but we still get the error.  I have even tried uninstalling Draftsight and installing the latest version and we still get the error.  When uninstalling, I try to delete any left over Draftsight directories and registry entries so that it is a clean install but still get the error message.

Could someone give me any ideas as to how to get around this error message?

Thanks,

Chris