Could it be this port 8000 is already in use?
Was the URL properly registered? Check this with the TMSHttpConfig.exe tool in the subfolder Bin\Win32
I can really not see any relationship between the use of a TWebButton component. Are you sure it concerns the same start URL?
First, no, the port 8000 is not in use and the URL is correct. I verify TMSHttpConfig.exe and this URL is in the list (implicit with * and explicit because i add the full URL in the list to force it).
I use the TWebButton in order to test the problem, but every new project with only one TWebButton or other component runs fine except my existing project.
But today when i try it all runs fine, my project too.
Is clear that the origin of the problem is in my user session of Terminal Server. Perhaps related of permissions...