Recent results on the running coupling in QCD with two massless flavours

We report on the latest results on the running coupling of two flavour QCD in the Schr\"odinger functional scheme. Results for the step scaling function are obtained from simulations on lattices $L/a=8$ and $L/a=16$ which confirm the first results from lattices $L/a=4,5,6$ presented one year ago by the ALPHA collaboration. We also discuss some algorithmic aspects, in particular concerning the occurrence of metastable states. A modified sampling, in order to estimate the proper weight of these states in the path integral, is proposed and tested.