Please help!! What is wrong with my seedlings

Hello everyone again!!
i am now on my second grow after having a few problems with my first. Everything seemed to be going well until I took them out of the propagator. As soon as I did the leaves started shrivelling up and I just put it down to the humidity whilst in the propagator. Since them they started to pick up but now try are looking really sick. Although saying that, the new leaves that are coming through look healthy. Please can someone help with this problem, help me identify what is going on.
I have not given them any bites except for formulex when they were 2 weeks old.
They are under a 150w hps bulb with temps at 27 degrees humidity 40-45%. They are in a grow tent with intake and outtake fans and they will be 3 weeks old on Sunday.

Any my help would be much appreciated.

Transplant into larger plantpots and get $5 hygrometer(s) at Lowes or Canadian Tire for watering purposes, one for each plantpot. You probably took them out to early. If they have shown new growth since you took them from the bin they will be ok. Spray them often with fresh clean water. This will help them cope until the root mass is fully developed. The temp should not be permitted to go over 80F, whatever that is in celsius.

Ok thank you for the advice. Yes they have lots of new growth since they have come out of the propagator, it's just seems to have effected the leaves that were there while in there.

You got bugs. Dust with Sevin powder or something comparable. Get Sevin at WalMart. BigSteve.