I was getting this strange error when using parl on a par file: Set::Object object version 1.22 does not match bootstrap parameter 1.21 at /usr/lib/perl/5.8/DynaLoader.pm line 245.

After searching the web, it seems this error is caused by an incorrect shared library file for some XS code. So I deleted Set/Object.so from where it sits in /usr/local/perl/... Then I got a slightly different error from parl, which indicated to me that par unzips its stuff in directories named like /tmp/par-$USER/cache-* So I reinstalled Set::Object and deleted all the /tmp/par-$USER directories. That fixed the problem.

So to summarise, I got the "object version x.yz does not match bootstrap parameter version a.bc" error from DynaLoader. I was able to remove the error by deleting the par unzipping directories in /tmp/par*. Hopefully somebody might find this useful.