no PC stated connected to 113 (DLP ) projector, very nice.
5 years old , lamp life 5000hrs, min.
no cable stated, VGA? DVI what>?
how long is the cable 6feet (2m) or 100feet, we surely cant guess what you see there.
did you test the projector any other good PC.?
did you read the manual first for picking how to select inputs.
did you RTM on resolution limits and set the PC to that.
max on proj. is 1920 x 1200 (very good)
did you buy it new or used?
did it work ever, (used questions)
lock (i clicked search manual and found) 1 second
read PDF page 20 in your manual
it tells you to push the source button,
I guess you never read the manual?