Logan's Shadow help please.

I got the game for christmas and it's probably my favorite PSP yet, it shows how well shooters CAN work on the PSP.

The only problem is I get to Act 2, Level 2 where you are supposed to remove the nose cone from a warhead, get to the warhead, start tapping X to remove the nose cone, keep tapping X, keep tapping X, nothing happens. I could be tapping all X all night but it wont budge.

I've read the walkthroughs and I'm not doing anything wrong, I think another guy had the same problem as me on the Logan's Shadow forum but I can't tell because the forum is so slow and deserted. I even tried restarting the campaign but it made no difference.

Can anyone help me?

No I'm sure you have to tap X on this bit because you get the tap X symbol come up. And if you press a wrong button then you have to start the process again but on mine it just keeps going.

I even watched a video walkthrough online and when he reached that bit he just tapped X for about 7 seconds and it was done. I've tried it for about a minute.

Has anyone else had this problem, it's really annoying, I can't play my new and (apart from the glitch) great game.