WordPress automatically redirects to 404.php problem

Hi there,

When I tried to access a .html file uploaded into a directory under my domain name, WordPress automatically redirects me to its 404.php page instead of displaying the .html file. I’ve checked that the file name is correct, and also tried to access it through the parent directory.

The page is over at:
http://www.teddy-o-ted.com/demo/rollovereffect/rollerovereffect.html

And I’ve tried to access it via the rollovereffect directory:
http://www.teddy-o-ted.com/demo/rollovereffect/

…but WordPress still redirects the browser to 404.php.

In addition, I’ve uploaded the identical file but with a .txt extension, and I can access the txt file, but not the html file.

Any solutions?

Thank you!

[Edit]And weirdly enough, I only get redirected when I’m using Firefox and not Internet Explorer 7. Now this is really puzzling.[/Edit]