Q: MacBook Pro screen blinks

Maybe things will get better when Lion launches?

For sure. I have no blinking with Lion, but just installed yesterday.

Interesting... I will try this and let you know if it's software for me too.

Done a few weeks of testing so I'm 100% sure that on my MacBook Pro late 2008 (MacBookPro5,1 -> Intel Core 2 Duo 2.53 GHz) the problem is software and starts with the 10.6.4 update.
Do the test, it will be a good idea if other people will confirm this.

Just take care when installing, do this on a new partition

For those who haven't had time to read the whole thread, many of us started experiencing the NVIDIA 9400 blinking 30+ months ago, which takes us back to Mac OS X 10.5.

Same here Scott. Back to 10.5...

Sounds great, but LION completely loses support for Rosetta. I still have dozens and dozens of apps still requiring Rosetta. So in order for me to get this blatant bug from Apple fixed, I'll have to "buy" a new copy of Mac OS X Lion and lose functionality with some of my much needed apps requiring Rosetta! Apple gets worse and worse everyday.

When I get the time, I'm going to try this and revert to original software that shipped with my MBP.

Actually, this started well before 10.6.4 came out. I had this issue back in 10.6 and 10.6.1 and everything following. The only OS versions I've not seen this issue with were 10.5.5 (came shipped with that) through whatever 10.5.x version was current when Snow Leopard shipped. I don't remember ever seeing a single blink before installing Snow Leopard.

So, I'm with you on this likely being a software problem. If not software, then firmware, as there have been a few updates since I bought this MBP in late 2008.

You are right. I'm also frustrated as I was very excited when 10.6 was out, I purchased the software and now, I decided to go back to 10.5 as I can't use the 10.6...
I don't understand how is possible to let this problem unsolved.

The only reasons I can think of that Apple hasn't resolved the issue are:

1. They have no idea what's causing the problem and have decided that it's not worth the time/money to investigate beyond whatever time/money they've already invested in this issue.

2. They know the cause and solution, but to implement them would cost way too much money.

3. They know that this problem won't cause them a significant loss in MBP sales even if they never fix it (can you say Titanium PowerBook paint issues?).

It'd be one thing if Apple had competition on the hardware front. Since they don't, they know that to run OS X we must purchase an Apple computer to do so. Yes, you can get away with running it on a PC by patching the OS, but most people won't want to go to that kind of trouble. Since they don't have any competition, then customer satisfaction isn't as much an issue as it would be otherwise. Where else are we going to go after all? Most users here would probably rather put up with the display issues than switch to Windows, no matter how frustrating this gets.

I'm on 10.5.8, just installed 5 hours ago and no blinking here... for now...
Do we all have the same hardware in these MBP late 2008? I bought mine in november 2008.

Right
I'll never use Windows. But I'm dual booting with a Linux

Any advice on the safest route to going back to 10.5? I have Time Machine also backing up my entire drive automatically.

The safest route is to either reformat your hard drive with 10.5 or install it on a different partition from 10.6. You'll need to manually reinstall your applications and manually restore your data files. Don't go anywhere near your time machine backup of 10.6 unless you're just going after data files. If you restore applications or part of the system, you'll probably trash your installation.