Rolling line We have a rolling line that starts at the bottom of the screen and slowingt rolls to the top and then starts over again. Why is this and how do we fix it?

If this is seen when you are connecting to a cable box or satellite box like DirecTV through or other such device your issue is most likely a DC ground loop. Here are some suggestions:
Video Projector ground loop
1) If you have horizontal hum bars when your projector is connected to a set-top box or other equipment that are on a different circuit or are grounded causing a ground potential between the source and the projector
2) Hum bars are the result of a ground loop, usually caused by cable television that has not been properly grounded
Try this to verify:
1) Disconnect your cable television coax from the wall by unscrewing it.
2) Run your Projector and verify that you are no longer getting the lines.
If you have verified that the issue was a ground loop by testing the solution requires a DC
Ground Blocker style device similar to the below options:
1) Go to http://www.cablesandconnectors.com/02100-02.HTM (part number 2118)
2) Purchase a DC GROUD BLOCKER & ISOLATION TRANSFORMER either from the above or similar electronics store location.
3) Other examples and ground loop explanations for both Video & Audio can be found at the following link for information about ground loop; scroll to Why Ground Loop is a Problem:
http://www.epanorama.net/documents/groundloop/index.html
4) Other commercial antenna signal isolators are available on the web or simply see your local Radio Shack
5) Connect the isolator device chosen to your set-top box and hook it back up.
You will be back-up and running in no time.

This occurs when the input frame rate is not understandable by the projector..try changing the settings in the input or in the projector

Try to tell me.... whether my suggestion was useful???

Bye

:)

Have a nice day.