Caps-Lock flashing 10 times, no display

Hello! The last couple of weeks my computer have had problems booting. The Caps-lock flashes about 10 times and then the computer automatically turns off. The screen is black, but the fans and HDD seems to be on (noise). The computer also locks up from time to time when in Windows. Sometimes the screen is almost white and sometimes there is a weird colorful figure on the screen. The only way to reboot is to press and hold the power button. I find it weird that the computer still manages to boot up after trying some times. So it does not seem to be totally dead.. I have a Dell Inspiron 6000. best regards, espen