table corruption

Hi,
i am using postgresql-7.2.3. One of the tables in my database seems to be
corrupted.
It has about 250000 records, but when dumping the table postmaster crashes
when querys exceeding row 152238.

"select * from prvlog limit 1,152238;" works fine

"select * from prvlog limit 1,152239;" results in:
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Succeeded.

The same happens to anything above 152239. (well, i didnt tried all...)
The first (regarding to the tabledefinition) 2 fields of row 152239 can be
viewed. Querying other rows show the above error.
There is no index on the table. Is there something i can do to rescue the
data?

Regards
Thilo