ExecEvalExpr: unknown expression type 704 problems

Greetings, it has been a while since I have been on any of these lists. I've
spent the last year or so working in a place that uses MySQL for just about
everything. This means that the last version of PostgreSQL I've seriously used
was in the 6.5 series (6.5.3 I think, but it's been a while).

I am working on a project where I want the features from PostgreSQL and pulled
7.1.2 from the ftp site, built and installed it. All went fine, no troubles.
[Found I was a bit rusty using some of the PostgreSQL since I got used to some
MySQL specific things, but that's another issue.]

I got the data loaded that I need to work with, and am having a problem with one
specific query. It keeps dumping out with ExecEvalExpr: unknown expressiong type
704. I've searched google and the only reference I've found for this in
PostgreSQL has been on the hackers list for version 6.5.

I have one big problem.

I have an ID column which is a bigint, and I have another ID column which was
created using SERIAL, so it is an integer.

Is it possible to use SERIAL to get a int8 datatype instead int (int4)?

Finally, is it possible to get unsigned integer data types in a table?

Thanks,
Greg