Weird Problems...Please Help!!!!

My 808ex has lost one of my samples into the digital abyss... Not real big prob as I can redo this. However, when I switch between pad banks and play samples, the machine lags slightly in the loading of the next bank of samples. Even worse, if I switch back to the original pad bank I am having problems with, and test the samples there, the sample will play, but it will add on the end of a sample from the bank I switched from! This is not puring playback of song data. Just sitting at idle. So I put in another disk with loaded pad banks, and the 808 will not let me switch pad banks. Any help would save my LIFE!!! I cannot live without this machine.