alfa2536,

On my system, the file /var/lib/mce/mode is owned by root, and writable only by root. There are many threads around to show you how to obtain root access, check them out. The easiest I found was to install openssh and then do:
You can use any text editor to edit the file. If vi is out of your league, you can simply use the following command ONLY if you are sure the file is empty. Running this command will squash all data currently in the file, so check it first.

Hope this helps.

*Edit: Upon further thought, while this fixed the problem for me also, I have no idea why, or how this occurred. I'd love to get to the bottom of this. I hate just changing configurations without knowing fully what they do, and how they changed to begin with.