Keyboard weirdness

my keyboard has a mind of it's own hence me only saying "hi all" in the previous dialogue box. I apologise for any mistakes or weirdness as sometimes it just does what it likes and I don't want to press delete unless I really have to. It is one of the plastic keyboards, the mouse plugs into it and works fine. The keyboard sometimes dddoesn't work at all, sometimes puts in extra letters (as above) or completely different letters or numbers. Sometimes when typing on websites or putting web addresses in it will repeatedly put in a random character and not stop. Sometimes pressing a key whilst on a website will cause the webpage to change, like hitting a link. I think it's probably time for a new keyboard but I thought I-§1234444444444444444444444444444444444444444444444444444444444444444444444444 444444444444444444444444444444444444444444444444

(sorry again, it went bad for hours) I thought I'd check on here in case there's anything else it could be. I've plugged it in to various usb slots and it's the same in all of them. Thanks for any advice

Hi and thanks.
I repaired the permissions yesterday while the keyboard was working and it has continued working fine since then. However it worked fine for 3 days then broke again last week so I'll have to wait and see.
I've restored all defaults I can find in the system prefs for keyboard and mouse too.
I'm not going to do the SMC reset yet as I want to wait and see how long the keyboard works for before I start moving the leads about again.

I think it's probably a slightly dodgy connection somewhere, I had a similar problem with my old G3 keyboard after my girlfriend spilt coffee on it. I'll post back with any news.

It's been fine since, repairing permissions is all I did. Cheers