So is there another user doing something on that table at that time? If not and it's only you, then something changed in the code, or an update to Access has caused code that worked before to not work as expected now. We've seen this happen when less than perfect code worked before but failed after an update. Or code was modified and now some action taken puts a lock on the table and subsequent code attempts to modify it independently. That has happened to me before. Suggest you step through and see what the sequence of code actions is.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.