Welcome to Adobe Forum,
Do you have beta(trial version) installed for light room? If yes, then uninstall it completely by checking the preference boxes too.
Now restart the computer & download & install from the CC desktop App. It should work.
In case it does not work, contact Adobe support at http://adobe.ly/yxj0t6.
I have windows 7.
I had already downloaded LR and the Photoshop CC when I purchased them both while I was still using the trial. I had no trouble till now. While working in LR it now won't let me cross over via the EDIT IN Photoshop CC. When I do the trial pop up appears saying I have expired. Yet I have purchased PSCC.
You were saying to uninstall LR but haven't been game in case I lose it completely. That is if I have understood u right.