Thanks for the response Patrick,
Yes, I have plenty of data connections in the form (11 in total).
Two of them are pointed at the user profile web service, and use the absolute path the to service: https://[Intranet]/[Subsite]/_vti_bin/userprofileservice.asmx?WSDL
Most of the data connections are pulling from SharePoint lists - (all absolute urls, to different lists in the same subsite): https://[Intranet]/[Subsite]
One data connection is used to submit the form to a forms library (again an absolute URL): https://[Intranet]/[Subsite]/[LibraryName]/
And the final data connection is to a local XML resource file.
There are no relative references in use. All of the Data connections are local, I've not converted any into UDC files.
I am publishing the form via a Content Type, which I've created in the site collection's root https://[Intranet].
In the Publishing Wizard, I am doing the following:
"Enter the location of your SharePoint or InfoPath Forms Services site: https://[Intranet] - NB, I'm pointing this at the root, and not the subsite - perhaps this is wrong?
Checked "Enable this form to be filled out by using a browser"
Selected "Site Content Type (advanced)"
Update an existing site content type
"Specify a location and file name for the form template": https://[Intranet]/FormServerTemplates/[Filename].xsn - NB, again pointing this at the root's FormServerTemplates folder - is this correct?
"The fields listed below will be avaliable as columns in SharePoint sites and Outlook folders": added c. 75-80 columns (all Site Columns created in the Site Collection root, in a custom group - all columns are either text, or multiline text (an attempt by me to try and keep the process simple!)).
I do hope this extra information might help someone point me in the right direction,
Thanks in advance,
Rob