Did either of you (theqwertyblog or reebzor) try a Mini-DVI to DVI cable - I bet it is something with VGA connection.
My monitor only has VGA input, I'm sure his does too.
Did either of you (theqwertyblog or reebzor) try a Mini-DVI to DVI cable - I bet it is something with VGA connection.
I have had this exact problem (on a PC) and have solved it. I recently swapped out a 15" Viewsonic lcd monitor with this Dell and I was too lazy to move the VGA cable. I was getting the same symptoms you are. PC goes to sleep and monitor shows the self-test screen. I figured it must be a missing pin or something in the cable itself so I swapped out the Viewsonic cable with the one that came with the Dell monitor. Now it goes to sleep exactly like it should.
So you should get the original VGA cable first and make sure that works ok on a VGA port. Then try your VGA to Mini-DVI adapter. If that doesn't work look for a VGA to Mini-DVI adapter that carries all the signals properly.