libpq crashing under Vista

I recently upgraded my computer to Vista. When I went to run my application
(which ran beautifully under XP), the release build (VC++ 6) crashes every
time libpq attempts to connect to the server I have running on localhost.
The debug build runs fine. Through logging, I've found that it happens
inside the PQconnectdb function and because I get no firewall notifications,
I know it's not even attempting to connect over the network.

I've tried using version 8.1.9 and 8.2.5 and get the same result in both.
If I link with the libraries included with PostgreSQL 8.2.5, it works fine,
but I'd rather have a statically linked version (my debug build has better
performance when linked to the static lib than the release build did linked
to the DLLs).

Again, this exact same setup with the exact same version of PostgreSQL
worked fine under XP. I'm new to Vista, so perhaps there's something I'm
overlooking. Any ideas or advice is appreciated.

Josh