Electric Dreams. Released in the early eighties, my memory is a little hazy, but I think that the plot goes something like this:
The main character is called Miles. He decides that he needs to get in to this new computer fad that's going around, so buys himself a personal computer with all the gubbins. Late at night, after setting it all up, he spills champagne all over his new computer. Naturally, this causes the computer to become sentient. Miles falls in love with the girl next door, who's played by Virginia Madsen. He then enlists the help of the computer - who's called Edgar by the way - to win her heart.
Unfortunately, Edgar also falls in love with Ms. Madsen, and begins to compete with Miles for her heart. After a degree of hijinks, Edgar realises that Virginia can never love him, so he sends a massive electrical charge through the 'phone line, around the world, and back to himself, whereupon he explodes. Miles and his lady drive off in to the sunset. But then, the soul of Edgar takes over all the radio stations in America, intercoms as well, and plays the song 'Electric Dreams', by Phil Oakey and Giorgio Moroder, to which the general population dance wildly.
I can't recommend this film highly enough; it's an incredible story that shows just how ignorant people once were about what computers could and couldn't do.