Problem of view with Desktop Client

Hi !
I've got a problem with my company's webissues. Someone must have touched something or whatever ; the problem is here. Our Desktop Client can't display an issues anymore. When your checking the different projet, none of them appear and when your crating an issue from this client the window that opens says the following 'Unknown Issue' and at the bottom 'This view is not accessible'.
The fact is, everything is created and accessible from the web client.
After an hour of reasearch in the logs and the settings we just give up.
Please tell me if you have an idea of what happened of what may be a solution.