I once had a problem like this, i never got to the bottom of it but it was fixed by installing Scalar::Util.
Class::DBI uses it if it is installed, but doesnt complain if its not, hope ths helps.

Update:
My mind is muddy, it may have been caused by *installing* Scalar::Util, i cant remember!, anyhow, see if it is installed, then install/uninstall to see if this fixes the problem.