Since you're using IIS, I'm assuming it's Windows NT: does the IUSR or IWAM account have write permissions to the file?

As for your HTML: It's tag soup. You need to end your tags before starting new ones. Also, character elements like B or I are not supposed to be nested, and should be inside block elements like P. (Yes, some browsers will handle bad HTML sometimes, but there's no quarantee or requirement that they should.) Look at the some HTML references.