Help me plsss...

Hello,
hi dj please help me... i have a problem with my computer, sometimes it doesn't detect the cd-rom, and it will not go to windows, then i change the 1st boot to ide, and it would just give me a black screen, but when i pull the plug off, then wait for a couple of minutes then turn it on again, it would reach the windows but it would take so much time,this problem comes back again and again, and now that i've reach the desctop, my computer runs slow, specially when i download using download manager... please help me, is it possible that my bios have virus? or is it possible for the bios to have a virus? please help me....