can't find files in pg_clog and invalid page headers

I am running postgres 7.4Beta1 and have found a problem, I'm not sure if
its a bug or something I did wrong.  I ran ANALYZE on a large table while
the database was receiving data, after running it on just my large table I
decided to run it on my entire database.  When I issued the database wide
analyze I got an error:

data=# analyze;
ERROR:  could not access status of transaction 739760128
DETAIL:  open of file "/usr/local/pgsql/data/pg_clog/02C1" failed: No such
file or directory

There is only one file in pg_clog its called 0000.  I ran it again and got:

data=# analyze;
ERROR:  could not access status of transaction 3942652937
DETAIL:  open of file "/usr/local/pgsql/data/pg_clog/0EB0" failed: No such
file or directory

Then I tried running analyze just on my large table again and got:

data=# ANALYZE "DetailedMeters";
ERROR:  invalid page header in block 10836 of "DetailedMeters"

Now whenever I try to read all of "DetailedMeters" I get that error message
though the block numbers can change (10832,10834,10836).

Anyone know what I did to cause this?  Or is this some sort of bug or
hardware failure?

---- Adam Kavan
---- akavan@cox.net