Hi, thanks for the replies! I'd thought the solution was gonna be to play often

Sadly I don't get a lot of chance to play in concerts. I guess I could try and get my teachers to arrange some stuff, or like you said ask my friends.
I don't think I've got any serious physchcological problems lol. Well, I've got tourettes syndrome I think, but I don't think that that should affect my performance much. I guess I have to hold the tics in cause I know that everybody is watching me, and that makes you feelquite tense and stiff which is unpleasant. But I don't think that that's the root of the problem.
I think I could probably try and play something a bit easier. I wasn't going to play that certain Chopin Ballade that I've been learning for ages that I'm in love with

but I was thinking of something like the first movement of Beethoven's Pathetique. I have played it in a concert last year, but it didn't go too well - apart from the fact I can't play anything smooth when nervous, I was playing on an electric piano, and when I crossed my hands over the one time I caught a button and a drum beat and all these chords came on

I went back to start of the section though and picked it up suprisingly well for me. I think maybe something quite a bit easier than that is in order. It's annoying, because I'll be playing on an electric piano, so I won't be able to play a slow piece and then try and play it really musically well because, well, it's an electric piano.
And yup, I mean the 26th prelude. He wrote 24 as part of op.28, then 25 in C sharp minor and 26 in A-flat major, both posthumous, as far as I know. 26 is a quite fast one with pretty much perpetual momentum the whole way through, which made it kinda difficult given my state at the time!
I was a bit worried though, because I thought that it might be something more than just nerves. Like I mentioned, everybody gets nervous, but it doesn't seem to affect their performance. Is it just that I've got 'em worse or something else? One worry for me is that next year I'll be off to uni (to study physics), and I won't have much chance to play piano, and probably next to no chance to play in front of people. Oh well!