Error -2147352567: Locked. Cannot update

[Lars Brownies]

In a subform I wanted to add a record to a childtable. When I started typing
Access freezes and after about 10 seconds, I got the trapped error message:

Error -2147352567: Locked. Cannot update.
I wasn't able to add a childrecord to any of the parent records. I was able
to update an existing childrecord though.

After a compress and repair action, it all works again.

I can't find the error number on the internet.

Does someone know what causes this serious error and what I could do to
prevent it? I've already taken actions to prevent corruption (BE-FE, unbound
memos, etc.)

Thanks,

Lars