Today one of my colleague, actually one of my bosses 🙂 was preparing a MOSS presentation and when he was Publishing a InfoPath Form to MOSS a strange thing happened.
The url inserted on InfoPath was http://SERVER/sites/xpto and InfoPath returned an error message alerting that there wasn't a SharePoint site on that url but on in IE it works just fine.
Then we discoverd the problem, the http://SERVER/ site didn't have a Site Collection created, when we've created the site collection InfoPath stardet working just fine :).