Hurm - my guess is that the rundll32 is a startup item that somehow depends on explorer and/or exposes a bug in Litestep. Grab Autoruns from sysinternals.com and check if there is any "rundll32" item in the startup list. If there is such an item try to figure out which program it belongs to. Check if disabling it helps. There isn't much else (besides wild guesses) that I can say at this point, let me know how it turns out.