If I use Computer Error and I choose to draw 5 cards, does my opponent also
have to draw 5 cards?  Or does he draw however many cards he wants?  I think
that my opponent would draw as many as he wants, but people have been saying
how this card is good in a stall deck, so I was wondering what the answer is.

For BOTH players, they may draw "UP TO" 5 cards.  "Up to" 5 cards means 5, 4, 3, 2, 1, or 0.  This is why it is not good in a stall deck.