Turn off the auto source selection in the projector menu. It is a catch 22. Many new laptops will not engage a secondary desktop or cloned desktop until they "see" a monitor (or projector) sync signal. If the projector is auto searching, it is also trying to verify there is a sync signal present. You can see where that could go on for infinity.
Once you've turned the setting off, select the input you are actually connected to manually (remote or projector menu). Once it is on and set only to that input, use your computer to turn "on" extended desktop or cloned desktop using the graphics card software (do NOT rely on F8 to work since it can sometimes be disabled in the software).
Also, make sure your desktop resolution is a setting the projector actually understands. Many new laptops are capable of much higher resolutions than the projectors. Start with 1024x768. This is almost a universal resolution for all projectors unless it's REALLY old.
Last, verify you are using the right cable. Older DB15 connectors are missing the sync pins needed for newer laptops and projectors (ie SVGA cables are a no go).
Hope this helps! Good luck!