I don't know if anyone else has had this problem but over about the 5 to 6 hours I have been playing Red Dead on the PS3 it has locked up 3 times. There does not seem to be any rhyme or reason as to when it locks up. So anybody else having this problem or just me?

Some of the reviews I have read mentioned that it wasn't all that uncommon for a lock up to happen once in a while (360 and ps3).  I personally haven't had it happen, but GTAIV does it occasionally on my PS3 so I wouldn't be surprised if it happens to me too with Red Dead.

I was playing my friends PS3 version last night, after he got it. We played from around 10PM to 3 in the morning and it locked up 3 times. He took the game back and asked for a new copy today before he went into work. I'll have to see whether this new copy freezes too, he's at work during the afternoon though. Might go over later on tonight. 
 
I just got home with my 360 version though, I've been playing for 2 hours with no problems

I've played about 6 hours on PS3 with no issues.

Just looking at this thread there are a couple of PS3 owners here who have the problem and a couple who haven't.  It might be helpful if those with or without the problem stated which model PS3 they had.  Since it only installs 600Mb, my guess is that it could be a streaming issue and those with older Blu-ray drives may be the ones with an issue.  This is a GUESS based on Rockstar's heavy use of streaming content off the disc.  

I've played about 3-4 hours of the singleplayer, and had it freeze up on me once so far. 
 
I'm on the PS3 Phat (80GB MGS4 bundle to be exact).

I played it for probably around 10 hours now on PS3, and it hasn't frozen up. however, going to the poker game in armadillo almost locks me up. I press Circle to play and he just stands that. Eventually he sits down. Also, the characters on the table have texture popping issues. Thats happened like 3 times or so. After i beat the table I haven't gone back, and nothing of the sort has happened again.

Never had freezing but the game crashed once while I was in Free Roam.

Mine has frozen so many times that I can't even play the damn game anymore.  I can't progress in the story if my game freezes every ten minutes.
Also, we're not the only ones having this issue.
 http://www.youtube.com/watch?v=L7xMF0apZDg
It seems like the discs have some issues, or so says that guy.
 
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I'm playing it on the 360.

Yeah to be more specific I am playing on a PS3 slim. Since I posted this it locked up on me one more time with a total of 8+ hours clocked. I think it is just a software thing on Rockstar's end that they will have to patch. Also after seeing some of the 360/ PS3 screen comparisons and this freezing issue I was about to go out and buy the 360 version... Alas  money constraints won the day so I am gritting and bearing it through the PS3 version. The lock ups haven't set me back too far and they seem to happen primarily on bounty missions so I guess I'll just keep plugging along. :/

" @sandal_hat: How long ago did you get the game? Can you not take it back and tell them that it keeps freezing on your PS3, and that you want the 360 version? I mean if you want the 360 version like you said. It will look a little nicer too. "