Kicked out of Modern Warfare 2 - Help?

[Eggboy'13]

I have no idea why, but whenever I start up MW2 on my PS3, and I am logged into PSN, the game shuts down and returns me to my home screen. If I start up the game whilst offline it works fine, until I am asked to log into in order to play online.

This is not due to internet connection issues. This is not the fault of my disc. This is not the fault of my console specifically, as a friend of mine has had the exact problem recently.

Can anyone explain to me why this is happening, and what I may do to fix it?
Thanks~

[ZombieDeadpool8]

Mmm, sounds strange, I'll see what I can find out.
EDIT- There are a few solutions. You could try deleting the game data, then reinstalling the patches, that seems to have been the solution on the various pages I have visited.

[Pleiades]

It's probably a long shot, but have you tried deleting MW2's system data (patches, installation, etc.)?

And if you haven't already, you might as well try rebooting your router/modem.

[Eggboy'13]

Makes enough sense. I'll give her a go.
Thanks.

Edit: Fuck.
Did not work..

[Pleiades]

Makes enough sense. I'll give her a go.
Thanks.

Edit: Fuck.
Did not work..

Sorry, I'm not sure what else to do. If I think of anything, I'll let you know.