2000 Jimmy SLT, Sunroof electrical Problems

I Have a Jimmy, 2000 SLT Automatic 4x4, The Sunroof is the GMC factory sunroof, The sunroof will operate properly in most aspects but when left 3/4 to full open, when the truck is shutoff and the ignition key is removed it will close normally and then start cycling back and forth until the battery is dead, please note that this only happens when the sunroof is in the 3/4 to full open position, other than that it operates normally, the only way to stop it from cycling back and forth is to go and put the key in the ignition turn it on and then either close the sun roof by the button on the control or by setting it only 1/2 open, then it will operate automatically and shut itself down, Has anyone out there had this problem with their Jimmy or know of what causes this to happen.

Thank You for any suggestions or help Any of You can offer

Drizzt2006