I recently experience a problem with the RDP client not passing the %clientname% variable when setting up a Thin Client running Win CE 6.0. 

Further investigation shows that the issue of the environment variable %clientname% not being passed through to the Terminal Server does not have anything to do with Win CE 6.0. The issue was caused by the specific build of RDP 6.0 that was included on the image of the new shipment of Thin Clients running Win CE 6.0. The specific build included on this image was RDP 6.0 build 9.  [more]

When I checked, there was a new image available for the HP thin clients from HP’s website. The new image included an updated build (14) of  RDP 6.0. This build does pass through the %clientname% environment variable and allows the scripts to function normally. Build 14 of RDP 6 was not available individually as a download from HP’s site. That means the only option at this time is to reload the entire image on the thin client.

When you download and runn the exe you will be given the option of creating an ISO, copying to a USB drive, or deploying the files to a network. I copied the files to a USB drive and then booted the TC to the USB drive. Note: that the USB copy completely formats your USB flash drive erasing any pre-existing data.