The bolts that attach the cranks to my bottom bracket keep coming loose. I have tried greasing the threads and the spindle and tightening, releasing, tightening etc. but they keep coming loose and creaking after only about 50miles. I am using a dura ace track crank on a race face BB.

which cranks and which bb...

they probably weren't put on tight enough in the first place
you got to get them on pretty darned tight
best to check exactly how tight with a torque wrench
everyone's specs vary slightly but i think they are usually around 300 inch pounds

also double check to make sure the tapers aren't already damaged
wait, is this even a square taper bb/crank ?

Tighten them down to the proper spec, about 300 in/lbs or really f'ing tight, and then don't touch them until you need to remove them. I had the same "problem" when I installed one of my cranks but it's not really a problem. As I understand it, the crank actually works onto the taper after you install the cranks properly, taking some of the load off of the bolts, which makes the bolt feel loose if you try and check them after installation and riding. It hasn't been this way with all of my cranks but just one of them and I haven't had any problems with it except when I tried to tighten it down after the initial installation and I thought the bolts were coming loose.

Sounds like your BB spindles (and probably crank) are toast. If they've loosened up that much, it's time to get some new ones and torque it all down tight the first time.