Canon Speedlite 580 EXII
 

I'd guess you've got the flash set to stroboscopic (it will say multi on the display), if you press the mode button and set it to either manual or ETTL it should go back to normal...

It's on ettl but still strobes when I test fire.. ??

Does it still strobe if you set the mode to "M" (manual)? Pages 24 and 43 of the handbook seem to be the key.

lol yep still strobes... What the hell have I done....

If there's a "reset to factory defaults" option, I suggest you use it. Sorry, can't be any more help.

It says in the extensive instruction manual that if you leave the batteries out it resets, I left them out all night, Im feeling it may be faulty so will take it in to be looked at, cheers all..:)

A thought has occurred to me, you haven't got the gun set to use some "modelling lamp" kind of function, have you? I wonder if the strobing is a quick burst so you can assess the shadow patterns before you take the shot. I know some guns have such a feature.

I have worked out that you can test fire it on camera but not when it comes off... strange as I wanted to use it for some shooting effects for a video.........

You used to be able to get little slave triggers that would set the flash off in response to another flash, say the built in flash on your DSLR. Cost just a few quid, no control over the flash output except what you set manually on the gun just a trigger.