Hi Guys, been following the forum for quite a while... (yet still a newbie... I know...)
I have the same sleep problem with my MacPro, and following advise on the forum tried to reset my PRAM - but I couldn't. I simply didn't get the second chime, and the computer booted normally.
To make a long story short, I did an Erase/Install for the whole system. Following that the problem remained, BUT - I was able to reset the PRAM. Once I did this the problem disappeared and it worked beautifully for a few weeks, UNTIL - yesterday I installed the updates from Apple and the problem has now reappeared, and as before I cannot reset my PRAM.
Note: before I installed the updates i did a 'repair permissions' through the mac os x install disk.
Other than this I made no other changes so I am certain that this is what caused the problem to reappear.
I hope this is on any help...