Wrinkly leaves and brown stem on my phalaenopsis?
 

I got this orchid as a present last September. It lasted till November and I repotted it into a general mix containing fir bark, coarse perlite, charcoal, chunky peak/sphagnum moss. I'd cut off all the awful roots at that time. I trimmed the stem down to that last node.

It seemed to be doing fine until about a month ago. The leaves are now doing this wrinkling thing and the stem is just brown. The aerial roots all turn dark green when I water (about once a week, I just let the water run through the plastic container then set it back in the porcelain one). It sits next to a window that gets 2-3 hours of sun in the morning.

Any help appreciated :(

Typically, wrinkling in the leaves is an indication that the plant is not getting enough water. Next they yellow and fall off. Granted, there can be other causes, but my guess is watering. Fresh potting mix can dry out much more quickly than aged, broken down mix or sphagnum moss, and it's not at all unusual to have to pick up the watering pace after repotting.