Cannot save "Untitled-4" under a new name.

I'm getting this error trying to run the HelloWorld.jsx Script on a Windows Server 2003 VM machine inside OSX.

I've been working with the server with no problems, having been able to test scripts to import XML, and export in various formats..

I had just written a Windows App test client in C# .Net, the aim being to develop an Object Pool to control multiple instances, and was going to use HelloWorld as the test script... and now this.

The same script runs perfectly well from the ActionScript IDE, both in the Windows Server and on OSX.

InDesign Server is running as a Windows Service.
I can view the WSDL on http://localhost:1978/?wsdl ... fine.

Any ideas?