We have a root level site collection http://root that we can publish IP forms to
without issue, and we can publish forms to sub-sites under managed paths, but
not to the top level site collection in the managed path.

It is recommended that we move all of our forms to the top level site collection
because we are starting to receive publishing errors when re-publishing the
content types to the sub-sites.

We have followed the following instructions:
turn off system event notification service.
tried creating a new managed path http://root/reg with a site at the reg level.

We have really no errors in the error logs or system logs.

The only error we get when we try to publish is there following URL is not
valid: http://root/reg.