WMS problem: works in ArcCatalog but not in ArcMap

[CoreyStaver]

I have successfully used WMS before but something has gone wrong.  I can create a WMS connection in ArcCatalog and am able to connect successfully and see the images in the preview pane.  But when I try to add the layer to an ArcMap project I get this error "Could not add specified data object to map".

I tried adding the layer by using the Add Data button in ArcMap.  When I navigated to the connection it is shown with a red X as being disconnected.  And upon trying to access the connnection I get the error message "Generic server error message".

Here is one of the URLs if it helps:  http://maps.unr.edu/mapserver/services/Imagery/NAIP_NV/MapServer/WMSServer?

This is a URL that I have used successfully before.  And it seems that ArcCatalog is still able to connect.  Any ideas what's going on here?

[AitorCalero_García]

What version of ArcGIS are you using?

The URL http://maps.unr.edu/mapserver/services/Imagery/NAIP_NV/MapServer/WMSServer?request=getCapabilities seems to work well.

Have you tried with ArcGIS Explorer or any other client?

I would also suggest to use Fiddler to capture the requests/responses from ArcGIS.

Hope this helps.