Upload file error

I can upload a file OK (e.g. gif file). It uploads and I see it has been converted correctly to the different sizes in the user directory and image ID directory. But the image display at the top of the display is a broken link, it points to:

//storage/users/2/2/images/13/thumbs/large.gif

i.e. it does not have the domain in front of the storage. But teh download link does manage to locate the file and download it OK.

I'm using IIS and PHP 5.2.2
I've tried changing the temp dir and all those paths with no success.

thanks
Alan