Fatal error after a system crash

Hello everybody,

My system crashed two days ago. After the system restarted, the
postmaseter also started without any error messages. The problem happens
when I try to
connect to the database using either psql or JDBC, it says

"FATAL 1: cannot open pg_variable: no such file or directory"

and terminates the connection.

Is it possible to recover the database to a "workable" state?
Because I forgot to backup for a few weeks, the latest dump is
quite out-of-date :(
Frankly speaking, I have no idea about where the problem is.
Hope this is not really a "fatal" crash.

Would any kind people here help me to recover the DB?
If the data are corrupted and the database should be re-initialized,
is there any method to retrieve the data as much as possible
from the old repository files?

P.S.
My system configuration:
Win2k server
cygwin + postgresql 7.1.3


Thank you very much!!

Feng-Cheng Chang