Are you sure you're doing it correctly. You don't give any details of process. I've never had any issue resetting pram. Just keep holding the keys. Do not release until you've heard the third chime. (note: if you continue holding it it will just keep rebooting.) if you can't reset the pram for certain I would bring your computer in. More worrying than this stupid sleep issue.
Hey...
I am sure I am doing the process correctly (cmd+alt+P+R) and I simply don't get the second chime... it boots up normally..
The thing is that after I did an erase install I had no problem resetting the PRAM and that fixed the 'sleep' problem... (until I installed the updates...)
So I really doubt its a hardware issue... and I am also really sure it is the update that brought it back...
Unless some better solution comes up then either I will try the erase/install again (errr) or I will wait for 10.5.3 maybe apple will fix it....
open for any suggestions... (i also reset the SMC a few times...)
Thanks