Wrong sort-order

Hi!

Iam again having trouble with my postgresql ... when I do a
"select * from mytable order by username" then I get a result that's kinda
in the wrong order ...

It seems to make 2 different sorted blocks ... one starts with records that
start with "0...." sorted fom 0-Z and the other one comes directly after the
first one and starts with "_" again sorted from "_" - Z ... that is very odd
...

Does anyone have any idea what happened here ?! Any index or something i
have to recreate for the table ?!? I have 10293 in the table the column i
try to order by is varchar(255) and I use postgres 7.2.1 on RedHat Linux ...
i just "patched" the maximum arguments for functions to 64 instead of 16 ...

Greetings ... Manuel ...