MBP stucks on blue screen on login, even after complete reinstall

Question

Hi everyone!
This is REALLY driving me nuts. Three days ago, I found one of my MBP apparently on sleep but with fans running full speed and unable to wake up. As usual, when this happens I just force it to turn off but this time after the Apple logo (OS loading) I got stuck on a blue screen before the login window.
*What I already have DONE trying to solve this (please read)*
- PVRAM reset
- SMC reset
- Full check with Disk Utilities (no problems)
- Started on verbose and single-user mode and done almost everything there (fsck, checking console.log, etc…)
- FULL OSX REINSTALL, erasing every partition (even "zeroing" the disk) and installing from external drive (installing from DVD didn't seem to work, but the optical drive is fine). Still same problem.
*Other symptoms*
- After waiting like 5-10 minutes on the blue screen, it shows the login window just fine and I can login. From there everything seems to work OK. I can use my computer "fine"
- OSX loading (gray screen with the Apple logo) takes forever
- Mac doesn't wake up from sleep
- It runs quite hot
- I can boot in safe mode, but the auto-check at the start of that mode doesn't solve the problem
- When it is stuck on the blue screen, no cursor is shown. If sleep mode kicks in, the computer freezes on the login screen, can't do anything.
At the beginning I said that one of my MBP was affected. Well, one day after the EXACT SAME happen on my OTHER MBP, EXACT same symptoms. (MBP 4,1 and 3,1 both on 10.6.6)
I think this could be a corrupt firmware (remember this happens even with the complete reinstall) or a really weird hw failure or something beyond the OS.
As you can read, I can use my computer (both). I'm writing this on it in fact. But I can't fully fix it and I have spend almost entire days on backups, possible fixes, forum browsing… really this makes my days a living **** (not kidding!)
Please help me! Thanks in advance (And sorry for my english and the long post!)

Answer 1

nachX00 wrote:
HD is almost empty. 10 GB out of 320 used.
Retail SL
Well, neither of those should be the issue.
Can't check the FW ports, as I don't have a FW cable (they are somewhat hard to find on my city)
The reason I ask is because there have been a few cases here where the initial boot process was searching and searching for a FW port, but the port was dead, and it caused long delays similar to yours.
No, no new HD or RAM, but is not stock HW (upgraded RAM and HD several months ago, never a single problem on either computer).
RAM may be suspect. Have you updated software recently? Some RAM can be compatible with an earlier OS, but then out of spec after an update. If you have the original RAM, I would put it back in and see if that's the issue. If issue persists, try removing one of the modules and booting; if that doesn't work, swap the module into the other slot. Repeat with other RAM module. This will troubleshoot the RAM and both slots.
There also seem to be a growing number of issues with non-Apple-branded HDs, so I'm not sure that can be ruled out. If you have original HD, and the time to put it in, and you want to get to the bottom of this, you may want to give that a try.