What Build number of Horizon Workspace 1.5 are you using?
1.5.0-1318295
Lee Anne has got a point here, we had an issue which has been fixed promptly. Please refer to this KB:http://kb.vmware.com/kb/2059293
Please note, if this is a brand new installation, it might be easier to just download the latest build with the fix, and disregard the workaround suggested.
