I guess there has not been a resolution here. I am having the same problem with a particular machine ( Have several that run ENVI without a problem).
On the machine that is failing, I have uninstalled and removed the Harris directory and reinstalled. Rebooted.
Tried to run envi, envi+idl, idlde, and idl command line and all fail simply saying 'Unable to license IDL Runtime'
The license manager connects to the server and I can view available licenses in the gui. I can ping the license server without a problem.
I have tried everything I can think of to no avail. The only thing I can think of is something is wrong in the registry?