There are bugs, and then there are DUMB bugs!
When you try to publish an InfoPath 2010 form to SharePoint, InfoPath may display this error: “The following url is not valid”, even if the URL is valid. The cause? This Microsoft article says its because InfoPath ignores your URL and instead checks to see if there is a root level site collection. In other words, if you entered http://yourserver/sites/site1, InfoPath checks to see if http://yourserver is a valid site collection. There’s no “rule” that says you must have a root level site collection in SharePoint.
The fix, according to Microsoft… create a root site collection!
Did it work? Yes, and the odd thing is I created a site collection without granting the users access permissions and InfoPath was now happy in spite of permissions.
For more info see: http://support.microsoft.com/kb/981854
And while talking about DUMB bugs…
How about this one… try to publish from InfoPath to a server that requires authentication… you get a popup for the username and password with a popup about “Getting site content types”. You can’t authenticate without cancelling the “getting” of content types. You can’t get content types without authenticating.
Actually this is dumb, but unlikely. In this example the user was in the Member group, but was not a site owner. The first time the wizard asked for credentials it was to confirm that the site existed. The second time was because the user did not have rights to publish. Still… it’s a dumb bug.