In illustrator CS when you save a file that has a tiff as a postscript or pdf the tiffs edges appear jagged. I can save the file down to illustrator 8 and the tiff looks great. What causes this and how can I fix it?

Also I've had a large illustrator file and when I tried to print it some of the information and text disappears or the art changes placement in layers. I have type on top of drawn art and the type goes behind the art. Everything is on the same layer in the palette and it appears correct on screen but when you print you get something different or it doesn't print at all. I can take the same file to Freehand MX and it's perfect everytime. Any suggestions?