Difficulty attaching 2x4s to poured concrete wall
The drill bits that come with the screws are junk.

Also if you don't have a Slotted-Drill-Sytem (SDS) Hammer drill then all you have is a drill that wants to be a hammer drill when it grows up.

I have one of the Milwaukee's like that and had the same problems until I dropped some money and bought a Bosch SDS. I wanted a Hilti but the price was a little high for a homeowner. Hilti is all our contractors buy for a good reason. They are the best. The Bosch I bought is a good runner up though. Makes a ½" hole 3" deep in solid concrete in about 45 seconds.

You could still use the semi-hammer drill but get your self some good carbide tipped drill bits and pack a lunch. 

Good luck!