the newest information I got was, that sometimes the "opm.db file" is the culprit. In this case you should delete it.
On the other Hand you should have a look at These links:
http://helpx.adobe.com/creative-cloud/kb/troubleshoot-cc-installation-download.html >>> Creative Cloud Help/Troubleshoot download and install issues
But as much as I regret it and as strange as it may seem I fear it's a challenge for Adobe's Creative Cloud Cleaner Tool.
Sometimes - for whatever reasons - CC doesn't "want" to work. In this case you should CC completely delete and reinstall by help of Adobe Creative Cloud Cleaner Tool. (A try to uninstall by own resources is not enough!)
I quote: ... helps resolve installation problems for Adobe Creative Cloud and Adobe Creative Suite (CS3-CS6) applications. The tool removes installation records for prerelease installations of Creative Cloud or Creative Suite applications. It does not affect existing installations of previous versions of Creative Cloud or Creative Suite applications.
Please use: http://helpx.adobe.com/creative-suite/kb/cs5-cleaner-tool-installation-problems.html and follow the prescribed sequence of operations
If necessary and for further questions click through http://helpx.adobe.com/contact.html and if "open" please use chat, I had the best experiences.