Trouble installing modules

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?