Strange. Please can you just try the steps found
here first, but for issues like this we really need to be able to look at your system files to help see what may be causing it.
Another good thing to try is to close Uplay, go to your cache folder in your Uplay directory and rename your cache folder to something like "cachebackup". Then see if you still have an issue.
If you have done those steps, please could you submit them
through a support ticket or contact us through live chat on the same link.
You can also private message us on
Twitter or
Facebook if you prefer.
You can find instructions on how to create the files and attach them to your ticket at the bottom of the first link.