ignore the notes?...

[stephen_g74]

Some keyboards just can't handle multiple keys being pressed at once. If you have any extra keyboards lying around your house, try them out. It might just be the keyboard you are using. I had to switch keyboards because I had the same problem.

EDIT: I am also using and emachine desktop, and the keyboard mentioned above that I had to switch out was the crappy emachine keyboard that came with the computer. So it's extremely possible that you are having the exact same problem as I had.