R SIG Debian - Nov 2007 - failure to update package on Ubuntu 7.10

I am running R-2.6.0 on Ubuntu 7.10.  I have successfully installed and updated
packages on Ubuntu 6.10 and 7.04.  I think I have also successfully updated
packages after upgrading to 7.10.  However, today I tried to update Hmisc, mgcv,
and tseries, and received the following error message:

/usr/bin/ld: cannot find -lgfortran

As far as I can tell I have gfortran installed.  I don't know R or Ubuntu
well enough to track down the problem.  Is this a known problem, or do I have to
set an environment variable or specify a special parameter to make to tell R
where to find gfortran.  Any suggestions would be greatly appreciated.

Thanks,

Dan

Daniel Nordlund
Bothell, WA USA