I do have some naive suggestions (that you've probably already gotten).
If you don't have manufacturers manuals for the projector (and for the computer),
get to the websites for them and download those (usually .pdf) or
check for FAQs for them.
I'd think the manufacturer(s) probably have troubleshooting guides
to lessen the need to deal with phone-calls for help.
Good luck and, well I suppose this is appropriate...keep the faith.
Also, use the power of Google (even if it will require some sifting on
your part):
E.g., use Google Advanced with "all the words" with something like this:
"digital projector" "troubleshooting"
to get this
http://www.google.com/search?as_q=%22digital+projector%22+%22troubleshooting%22&num=100&hl=en&btnG=Google+Search&as_epq=&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_occt=any&as_dt=i&as_sitesearch=&as_rights=&safe=images