bugs in labels

when trying to label songs (control B or M), program won’t accept several letters - like J and K.

Those are actually Hot Keys for something else. Which version of Audacity do you have? I think it’s Help > About Audacity. Something like that. Koz

This is a known issue. See here for how to work around the problem:
http://wiki.audacityteam.org/wiki/Release_Notes_2.0.2#Label_Tracks .