Sonar 8 widget tab manager is empty

Well, sorry for a post from an old Sonar, but it's also working for me and I don't want to change my workflow.
I'm using Sonar 8 on Win XP for a long time, but suddenly the widget tab manager is empty.
 
I was ready to chenge one of my customs tab in the track view and there is nothing inside the manager. All tabs are ok, including my custom ones, bu when I right click on any tab and go to the widget tab manager, everything is empty. No widgets, tab names, nothing.
My tvwidgets.xml file is there at the DATA folder untouched.
Anyone know what's going on?

Alex