install.php gives blank page

I’m running IIS 6, PHP 5.2.1, and MySQL 5.0.37
[updated] Oh, and I’m trying to install WP 2.1[/updated]

[updated 2] after searching the forums, some additional info so folks don’t chase the wrong thing.
PHP.ini is set to 128meg memory and I have BOTH mysql and mysqli extensions loading[/updated 2]

I’ve created a wordpress db in mysql and a wordpress user with all permissions to that db. I’ve gone so far as to create a test table in that db and hand write a short script in PHP to pull the record I inserted just to make sure that PHP was accurately connecting to mysql and obtaining data using the connection parameters I have in the wordpress config.

Here’s where it gets REALLY wierd.

If I just go to the root of the wp folder, I get the “not installed” message. Click the link and I get a blank page. Nothing comes up. If I go back to the root folder of wp THAT PAGE NOW STAYS BLANK TOO; and only a restart of services will get it to come back.

I suspect this is some bizzaro IIS prob, but why then do my handwritten scripts access the db just fine?

And why am I not getting ANY errors?

Any help is appreciated.