Upgrade of desktop boxes to Debian Lenny is still in progress - see also the ReleasePlan. If you are experiencing problems create a ticket, or contact the LinuxGroup directly.
InteractiveMachines lists the central Lenny nodes available for login.
Troubleshooting
g77 disappeared
g77 is no longer part of the GCC suite and has been replaced by the Fortran90 compatible gfortran.
For code that can only be compiled as Fortran77 take a look at f77, a g77 compatible frontend for f2c.