Hi .. quick advice needed

my webcam has started playing up and havent a clue why.
when i try to use it through messenger it looks like its about to connect, but then all i get is a black fuzzy screen!
any ideas ....only thing i have done different is updated norton yesterday....not sure if this would affect it.
by the way when i look at cam on video companion its fine and i can see myself....so not sure why its doing this with messenger.
camera is logitech 4000 if that helps
ta

try going to control panel-system-hardware-click on device manager-then click on view and click on show hidden devices so that it has check on it-u should find u webcam in there-first try re-intalling the softwear and if that dont do it try unistalling it then try it