Have a Salsa Casseroll that I have set up as a 1 X 9 for commuting.

Front: 45t
Rear: 11-32 LX 9 speed
Rear Der: LX 9 speed
Chain: Ultergra / LX 9 speed

Set it up with a chain right out of the box (minus a few links). Ran it for almost 300 miles with no problems - even tried a 42t Biopace for a few rides.

Then I cleaned the chain to remove all that packing grease and lubed it with Tri-Flow. I've gotten thousands of miles out of my chains like this.

Well, ever since I've been throwing the chain off the chainring. When it happens, it happens when I'm around the middle of the cassette shifting to a smaller cog. It throws the chain off the chainring to the outside.

Everything seems to be adjusted and lubed just fine. It would be possible to remove one more link, but not 2. Is that the problem or something else? Could the packing lube left on the cassette be doing it?

Thanks.