Help! hybrid Mtssa x Odm Bictoniese leaves dying
 

I was given this orchid as a gift and about two weeks ago the leaves started turning yellow and now have light brown areas. It is kept by a eastern facing window,generally have 40% humidity in house, 70 degrees during day and close to 60 at night and I keep ceiling fan going all day. I water about every 7 days. I also have another hybrid orchid of about the same variety that is doing wonderful. I don't know what to do. Please help.

I'm not sure if that's rotting, or if it's something else -
I would pull it out of the pot to see how the roots are.

I would also check the roots.
Joann

Thanks for the help. :) I checked the roots and they seem mushy compared to my other orchid. What should I re pot it in?

It sounds like you've got a bit of root rot. You'll need to clean up the roots and repot in fresh medium.
What is your other orchid potted in? If you're comfortable with that medium I'd stay with it. If it is sphag I would probably repot in medium chunk bark.
Joann