I think it's time for this problem to have its own thread. WB5 works fine on my account both at work and at home. None of the versions released so far work on other users on my home machine. Builds a - c will not allow limited users to open wbconfig. This morning, I tried build d which again works fine on my account (admin). I tried running it on my wife's account (also admin) and it simply stopped responding. I wasn't able to kill it through task manager either.
Rolling back to 4.6 fixes things every time. I'm running XP Pro service pack 2.