Really thanks Archie, you helped me to solve the issue. I suppose these are the things you cannot prevent, but learn how to fix.
Just for sharing, I tried deleting the OBJ and BIN folders from the project folder and hit rebuild the solution, but had no effect.
What it worked was to check the Designer.vb file after adding a new datasubscriber and compare against the code of the old datasubscribers controls, so I could note there was a lot of code missing for them. I just copied it and changed to the appropiate control name, and everything went back to normal at the designer view!!
Really appreciated!