Hi José,
did you try to research the IIS-Logs of the sharepoint-server to check if the client tries to load them?
What you can do next is a fiddler-trace of the client request in combination with uag-debugging as described here:
http://blogs.technet.com/b/ben/archive/2011/08/08/enhanced-tracing-for-asp-debugging.aspx
Regards
Thomas