ERROR: bt_fixroot: not valid old root page

Hi,

I'm getting the following error message and am hoping that someone can
tell me why and what to do to fix it:

adb=# select * from user;
userid | username | passwd | firstname | lastname | email
--------+----------+--------+-----------+----------+-------
(0 rows)

adb=# insert into user values (100,'admin','blah','ad','min',
adb(# 'me(at)email(dot)com');
NOTICE: bt_getroot[booker_user_pk]: fixing root page
ERROR: bt_fixroot: not valid old root page
adb=#

I'm running Postgresql 7.2.1-2 under Cygwin on Windows 98se (Just
playing with some stuff). I have cygipc-1.11 installed and running.
Nothing additional appears in the logs. Have plenty of disk space and
memory free.

If anybody requires anymore details please let me know.

TIA,
Trev