Popping sound coming from controller/computer

[Creationx9]

I have an old Kaysound keyboard controller which works fine. The only problem I'm having is I get a popping or click sound every time I release a key. So if I'm work in my notation program, which happens to be Sibelius.7, and I press a key on the keyboard to enter a note, the note does go in when I press the key down, but when I release the key I get this popping sound. This happens with every key. When I check the midi window,(I have a Mac mini computer) every thing seems to check out fine.
Anyone have any reason why this could be happening?
Thanks.

 

[Creationx9]

No need to reply. I figured it out. For some reason the popping sound I would get when I released a key on my keyboard controller would not happen when I booted up my computer. It would start to happen when I went into my audio/midi window and starting checking to see if the midi connection was correct. The connection is fine and now I don't go into that window any more unless I have too.