20D 17-55/2.8IS and Err 00 and Err 99

Hi, My 20D and 17-55/2.8IS combo is malfunctioning! On the 17-55/2.8IS when I have the IS on, sometimes the motor goes crazy and bounces the view around making it not usable. I had to turn off IS. After that my 20D also started working strangely giving some Err 00 that I had to fix by taking out the battery to reset. Then I started getting Err 99 and the view is very dim sometimes even after I take out the battery. I think the mirror is stuck or something. I manage to fix it by taking out the battery, putting it back in and then running sensor clean.

So any idea on what is wrong? I think the IS on my 17-55/2.8IS is dead (third time), but now my 20D seesm to have problem too.