Please help...

[menacinglove]

i have an I book G4. The other day i was online and my computer froze up, saying i needed to restart the computer. Everytime I i restart it, it freezes again within a few minutes. Yesterday it wouldnt even start up, and today it worked for a little while. I need help, and i have no idea how to fix it. i haven't downloaded anything i a long time, but it might still be a virus, i'm not sure. The bottom of the computer was also really hot, too hot to touch. Even after i had left it off all day. please let me know what you think i could do.

[icecube]