Yes, very weird. Some questions:

With a name like jester7677, I should ask if you're kidding! :-)

Did you try any/all of the other optical inputs on the 990?

Did you try connecting it with coax? Any old RCA cable will do for testing purposes.

Do DD5.1 programs come through and does the 990 automatically switch as it should?

I connect my cable box with toslink and like Gonk default to PLIIx, but I sometimes do switch to stereo and upsample for their digital music channels and it all works fine.