MAudio 2496 issues

Several in fact. :( (1) I get a random, single crack from one channel of the card, only while in SONAR X1 Prod. It's about every 10-30 seconds apart. (2) When I turn off the PC, I get a resonant, tuneful flatulent sound from the speakers. It lasts about 5-6 seconds. Both of these problems have occurred with two different 2496 cards. (3) I have tried to instal the latest driver and it says I have a side by side error and will not run. I have tried moving the card to another slot, reinstalling it, changing latencies for the SONAR cracking problem and contacting M-Audio support. So far none of these has worked. So if anyone has any ideas about any of the problems, I would really appreciate any help.