Problems with note input on MIDI Keyboard

Hey all,

Recently I've been having trouble with note input on my MIDI keyboard. I usually use it to input notes into my scores by using the manual beat advance. I hit a note, hit the 4th pad on the keyboard, and it advances a beat. Pretty simple, that's how it should work.

However, starting today it has been acting up. At the beginning, when I hit a note, it enters into the score, and then I hit the pad to make it advance to the next beat. However, if I exit the manual beat advance mode and go back into it, I can no longer enter notes into the score with the keys on the keyboard, and when I hit the advance button (the 4th pad) it skips a beat and enters all the notes that I have played on the keyboard into the next beat at once. When I hit more notes, it almost like it "adds" those notes to the notes that are played when I hit the pad to advance. Eg. I'll hit a D on the keyboard and it won't be entered into the score, but when I hit the pad, it will skip the beat that I'm on and enter it into the next one. Then, when I hit an A, nothing will happen like usual, and then when I hit the pad it will input a D and an A into the next beat, and so on. Sorry if this doesn't make a lot of sense, this issue is so odd and hard to describe. Not only that but it is possibly the most frustrating thing to deal with ever. I can no longer input notes into scores in the easiest way I know and my composition has slowed to a crawl.

The keyboard I'm using is a AKAI Professional MPK mini.

Please help.