I recently bought a new 27in iMac and installed my existing version of CS4 on it - no problems. I then bought the 5.5 upgrade disc new. Installed fine but recurrently quits unexpedtedly. After searching, it seemed that this was probably a problem with Lion. So - got my money back on the iMac, bought another with Snow leopard, got a refund on the 5.5 disc and bought another new one. I have now installed this as an upgrade from CS4 and have exactly the same problem. I have updated to 5.5.2 but no help.
What I need to know is whether this is a soluble problem as I will otherwise need to look at alternative software which would be a great shame as I am very fond of Premiere. Adobe support has been unable to help. Apple have nothing to say.