Previous install was 1.2.2. It went in without a hiccup. Pulled its strings for a few days same result... worked flawlessly.
Decided to up to the 1.5...snatched it for nightlys then dumped into dirs and hit the "upgrade.php" page and:
Fatal error: Call to undefined function: __() in /www/xxx/xxxx/htdocs/blog/wp-admin/admin-functions.php on line 857
I killed the dirs and database tables and did a fresh install of 1.5 and it installed without a hitch.
Have no idea what happened just wanted to throw that seed out there incase it reared its head for others.