Originally Posted by Notsobright
COD4 crashes and closes and it takes me back to the XMB on my 60gb. it happens mostly whenever i refuse to join friends party invites. happened 3 time yesterday. its annoying. what gives?
If you use a router then you might try checking your Network Settings on your PS3. Look for your NAT type.
Your NAT type should be 1 or 2. If you have NAT type 3 then you can have connection issues in general, and voice chat won't work. If you turn off UPnP then that should take care of that (worked for mine).
If you use a router then the PSN, and COD4, need to have ports open to run better. For mine I assigned my PS3 a static IP address, then enabled DMZ on my router and set the PS3 as its user. Basically, DMZ opens ALL ports for whatever is using it. Bad for a PC because it leaves you open to viruses. It's great for PS3 because you don't have to worry about a virus, and all games should run better without having to mess with your router.
I went to this site
and it was super helpful. Good luck.