Stange PHP bug?

Hi There, I'm developing a website for my boss, and it works PERFECTLY for me and everyone else i've shown it too, but when my boss goes to the page anything that is PHP related just doesn't show up on his machine. He is using Windows XP with Explorer 6, just like my development machine, but no PHP or Databases show up, it's just either the background images OR after an hour he gets a timeout - but he's the only person who has this problem. Has anyone seen this before? I'm sure it's not a PHP/MySQL error as a script either works or it doesn't, could it be his installation of Explorer? He's on dialup in the UK, but my friend from the UK is on broadband with the same setup and it works fine for him. Sorry this isn't an actual PHP/MySQL technical question, but I thought that somebody might be able to back me up as I think it's his browser. Any thought? Chris