Hi,
Sorry, i did not read you question properly ( tired from work i guess 

 )
the script is probably 
i have not worked yet wit a mouse orbit script but
maybe you can try disabling the script when tweening and enable again when done?
To try this Drag the script (on your camera) into a state before the tween and click set property, 
then select the enabled property
if that does not work can you attach a sample scene or the mouse orbit script?