WMS not displaying in ArcMap

[JB1]

Hello,
Running ArcGIS Server .NET 10.0 sp 3 build 10.0.3.3600 Windows Server 2008 R2. Customer indicates they can connect and add our WMS enabled ArcGIS server service with no errors, but no data is displayed in ArcMap. A get capabilities returns valid xml. The mxd the service is using contains UNC paths with the hostname.domain.xx.xxx The service's properties are also using hostname.domain.xx.xxx Some users can view the WMS. So not sure if it's a site firewall issue or a configuration on our end.

Accessing the http://hostname/ArcGIS/rest returns Error Invalid Code 404 - not sure if that is the cause or a differet issue.

I'm reluctant to run an ArcGIS Post Web install as this is on a production server. I cannot provide a link to the WMS in this forum.

Thanks in advance for any help

[RichardHughes3]

I too am unable to view WMS 1.1.0 or 1.3.0 inside of ArcMap 10.2.  Both my GetMap and GetCapabilities work in a browser and I can view the the images inside of MapServer for Windows.  They are being served by Apache so my situation is a little different. 

The problem is the same though, that the images are not being displayed inside ArcMap.

A GetCapabilities request is being sent to MapServer successfully from ArcMap.  There is not record in the logs
of a GetMap request being sent at all.

Richard