[SilverSmoke]

First of all, stop using a curl machine. There are several fairly decent excuses to use machines for some parts of the body but I really don't see why you just don't pick up barbells and dumbells instead of a bloody curl machine to do your biceps. In most cases, free weights are superior to machines for loads of reasons.
To be honest I really don't know why you seem to be injured (if you are, maybe it is just the normal pain you get after a bit of inactivity) as I've never used a curl machine, we don't have one in the gym. Does it force you to straighten your arms completely flat when you stretch out? Where do you feel pain? in the bicep or inside the elbow? Or is it the lower arm part?

Besides that, what does your biceptraining look like during a week? You do 5 sets in the curl machine to return back to it later to do some more every trainingssession?