I'm having what looks like a very similar problem installing several different modules. It has happened the same way on two different machines running Mac OS X 10.6.4 immediately after installing DBI. I don't know if it's related but, on both machines, I also lost execute permission on /usr/bin/cpan immediately after installing DBI but it was restored when I used the repair permissions function of Disk Utility.
The error messages I'm getting are things like: ****** WARNING ****** Space detected in path '/Users/af/Library/Application Support/.cpan/build/PDL-2.4.7-_V_tCx' PDL may not build correctly! Then there are a bunch of errors like the following: Could not read '/Users/af/Library/Application Support/.cpan/build/....' Falling back to other methods to determine prerequisites Then the module fails to install with: Running make install make test had returned bad status, won't install without force What's the best way to troubleshoot with this?