After publishing a lot of InfoPath forms, suddenly InfoPath 2007 started to present me with an error:
The following URL is not valid:

InfoPath The following URL is not valid

The error made it completely impossible to publish any document to my SharePoint site. After searching some time on Google I found a few solutions which didn’t work for me:

But the post from Firedancer worked all right.

The solution is to stop the System Event Notification service. It seems to me that it is more a work around as a solution, so after publishing enable the service again.

[update 15-11-2007]
You’ll only have to stop the System Event Notification service for one time. After you published the form resume the service. All new publications will go allright again. I guess that something that went wrong in the SharePoint database gets fixed after the forced publication.