Hi,
This is an odd one. I have about 40 Infopath forms posted to my SharePoint site (SP2007, InfoPath 2007) and I have one libary that is having this problem. All forms and libraries are configured exactly the same. Basically a form gets submitted, and remains checked out to the person who submitted the form. All the libraries were experiencing this problem until I put a pause in the workflow (10 minutes) on form submission, which resolved the problem on all, except for this one library.
The library is set to no versioning and not set to require documents to be checked out before they can be edited.
Is there anything that can be done to fix this problem, or should I simply recreate the library and hope that this fixes the issue?