I think all Poser 4 users have experienced a corrupt rsr from time to time, but if this is hapening all the time with any obj/rsr then you have a serious problem.

I would sugest you try an "over the top" reinstall of Poser, that is to say reinstall Poser without uninstalling it. This will overwrite the critical Poser files. Reinstalling won't delete anything from the library, but it will rewrite any poser content you have modified.

If that does not solve the problem then the only other thing I can sugest is to contact Curious Labs tech support.