I tried some reports this morning and got the same error....I did notice that when I opened my ACCESS database, my object.view was set on the reports. I set my object. view to my tables, saved, and reran the VB application. They work!
For what it is worth, I think ACCESS may be locking at the object.view level, if there is a change to reports. Even if you save your report changes, ACCESS may not want to release it???
This could explain why I see the problem, intermittently.