Here is a good one.
I have a MS Power Point dataset that was originally checked out using the MS Office client. The user went home for the week-end and came back on Monday without closing his Teamcenter session.
Noew the datset is shown as checked out, but if I try to check it in... quess what! the system says "Object is not checked out". But I can see from the icon and the properties that it actually is. All check-in and out, cancel fail.
Any ideas? or do I log it to GTAC?
With my previous customer, I had come across this problem for field engineers who were using MS office TC integration (through TC add-in) and there were frequent problems of the nature you reported.
I would suggest to report it to GTAC as this is a common use case for people working with MS Office.
In my view, the 'de-links' typically occur because MS Office Integration is based on 'OAI' architecture.
To fix this issues, I had in past executed the 'dataset_cleanup' and 'purge_datasets' (on prod replica db first) to sync the Teamcenter visual flags...in some cases, update of checked_out attributes was also required.
Let us know how it works out for you.