Here's a response from a member of the Microsoft InfoPath team that I had look into your situation:
Hi Greg! I have been able to test but have not been able to repro…here is what I tested:
- Created and published an InfoPath 2003 XSN, with a Submit connection, to my MOSS server
- Without any Office 2007 applications on the computer, the form opens in InfoPath 2003, submits without issue and contains the appropriate "href" PI
- Installed just Excel 2007 (from the Office 2007 suite) with SP1
- Clicked New to create a new form and submitted this to the library - result: submitted without issue and still contains the appropriate "href" PI
- Installed stand-alone Microsoft Project Pro 2007 with SP1
- Clicked New to create a new form and submitted this to the library - result: submitted without issue and still contains the appropriate "href" PI
- Removed Excel 2007 and left Project 2007 (this caused a reboot)
- Clicked New to create a new form and submitted this to the library - result: submitted without issue and still contains the appropriate "href" PI
Like you, I have not heard of this issue either so if this is indeed reproducible for that user they should open a support case with us so we can dig into this and either determine what I am doing differently in my testing or if there is something specific to their environment.
Thanks for your patience!
You might try doing an Office repair, or reinstalling InfoPath. You might also try reinstalling SharePoint and making sure that it has all of its patches. If you still repro the issue, please contact Microsoft Support for further assistance.
Good luck!