Failed Regression Tests due to SQL-Errors

After compiling and installing postgreSQL 6.5.1 on my linux box (SuSE Linux
6.1, Pentium II), I tried the regression tests. More of the tests failed,
than were ok and I checked the regression.diff - file to get more
information. I realized, a lot of tests failed, when making for example an

INSERT INTO CHAR_TBL (f1) VALUES (2);
instead of
INSERT INTO CHAR_TBL (f1) VALUES ('2');

(See the difference at the writing of the value 2, one time with and one
without apostrophe)

According to the SQL-command file it must be possible, to use both syntaxes,
but why do I have the problems.

The error code in the upper case is:
"ERROR: fmgr_info: function text: not in internal table".

If I do the same with a varchar, I even get the error message:
"pqReadData() -- backend closed the channel unexpectedly.
This probably means the backend terminated abnormally
before or while processing the request.
We have lost the connection to the backend, so further processing is
impossible. Terminating."

Can you help me?

Thank you very much

Michael