imac install

[peter rosewell]

sadly i have now given up on install of yd3 on my 15in imac tft.having
exhausted my miniscule knowlege of linux.it still does not recognise my
monitor.i have to install in text mode then as soon as i log on in graphical
mode the screen shows a scrolling logon screen in 4 sections across the
screen,making it unreadable.i really dont need 6 more coasters so can
someone please HELP!!
thanks 
pete.