The first link notes someone that deleted the files in a specific subdirectory. Have you done this and did you try the other things people have noted to cure this?
I am fairly new to Linux but am finding it very enjoyable. Currently I am running the newest release of Ubuntu and it works great. I dual boot with Windows 2000 Pro on a large Sata drive.
I needed a proprietary program and was unable to find it in repositories so I installed the CNR client from cnr.com. I was able to use this app quit well, at first. But now icon is black instead of green and anything I try to install using it comes up with error " unable to write to data base". I tried to uninstall through add/remove, no CNR remove link. Need help to uninstall. Reinstall failed also. Can not find help for this problem on their site or forums either.