IMac freezes after 10.5.7 update, should I roll back?

Question

I avoided doing the 10.5.7 combo update because my son's Macbook had issues with it. But I finally caved and, of course, now wish I hadn't.
When iMac goes to sleep, the power light glows normally, but when I press a key to bring it back, everything goes dead. Have read a lot on here about this and tried resetting PRAM and repairing permissions, neither of which has worked. The only thing I can think of to do is keep the sleep function on Never, which doesn't seem too healthy.
iMac is also almost five years old. Wondering if I should roll back to 10.5.4 which is what I had, and, if so, how to do it?
Also, I've downloaded the Safari update, which I know won't run on that, so would I even be able to get the old Safari back? Or has anyone figured out a surefire fix for this sleep issue?
Thanks,
Joanne

Answer 1

Hello Joanne:
A suggestion - reset the SMU:
http://support.apple.com/kb/HT1767
If that does not help, let me try to answer your questions.
Wondering if I should roll back to 10.5.4 which is what I had, and, if so, how to do it?
If you have Time Machine, use that (a copy before the problem). If you do not have TM (or a bootable clone) the way to go back is to do an archive and install:
http://support.apple.com/kb/HT1710
Also, I've downloaded the Safari update, which I know won't run on that, so would I even be able to get the old Safari back?
The archive and install will do that. By the by, Safari 4 should run just fine on your system. It is faster than Safari 3.
Barry