It seems possible they just went into shock when you switched them to HID lighting.
As far as venting goes...from the pics I see I would recommend this:
In pic #2 where the two holes are?
Have a exhaust fan there as well, with larger holes.
The exhaust fan on the top is sounds to me like it is not pulling enough air through the holes you drilled.
Try making them bigger or adding more of them.
If this will comprimise your light integrity than build some ducting with a bend in it to block the light, not the airflow.
I sometimes use cardboard and masking tape to build temporary ducting untill I can figure out a less ghetto HVAC solution.
Hope this helps, just from what I can see in the pictures and by what you describe...Fresh air and shock seem to be your only issue.
The plants look pretty good to me, maybe pull the branches apart or spread them so you can get that penatration.
You will definatley notice a difference compared to T5's.