Any real known bugs about wrong selects?

Hi,

we are currently using another database product but besides some 
licensing issues we are finding more and more problems with the 
database. We are evaluating PostgreSQL and it looks quite handy. 
Interesting features paired with good performance and a lot of users 
seems to be a prove for the quality.

I wonder if people encountered bugs like 'a select returns a wrong 
number of rows' or any other very serious bugs. We do not have problems 
with things like database crashes (because we already needed to check 
and fix such things with the other database product) or with slow 
execution time in some cases but we take it very serious if a bug 
results in -wrong- result sets because we are calculating bills and 
other things which is very sensible to wrong results from select 
statements.

As PostgeSQL is not a commercial product i hope that we are getting 
real, more reliable answers about bugs than from the database producer 
whose product we are using since now.

Regards David