Cannot delete value from index

[foosh101]

I get the following sometimes when I try to either remove a record from a table or drop the entire table:

<!-- 006 /texisUpdate/DelByID:24: Cannot delete value (Elwood) from index d:\morph3\texis\mktDB\mkt2000000LocationCity.btr -->
<!-- 006 /texisUpdate/DelByID:24: Cannot delete value (Park Forest) from index d:\morph3\texis\mktDB\mkt2000000LocationCity.btr -->
<!-- 006 /texisUpdate/DelByID:26: Cannot delete value (San Diego) from index d:\morph3\texis\mktDB\mkt2000007LocationCity.btr -->
<!-- 006 /texisUpdate/DelByID:27: Cannot delete value (San Diego) from index d:\morph3\texis\mktDB\mkt2000000LocationCity.btr -->
<!-- 006 /texisUpdate/DelByID:29: Cannot delete value (fairview) from index d:\morph3\texis\mktDB\mkt2000014LocationCity.btr -->
<!-- 006 /texisUpdate/DelByID:30: Cannot delete value (fairview) from index d:\morph3\texis\mktDB\mkt2000000LocationCity.btr -->
<!-- 006 /texisUpdate/DelByID:26: Cannot delete value (El Paso) from index d:\morph3\texis\mktDB\mkt2000007LocationCity.btr -->
<!-- 006 /texisUpdate/DelByID:27: Cannot delete value (El Paso) from index d:\morph3\texis\mktDB\mkt2000000LocationCity.btr -->
<!-- 006 /texisUpdate/DelByID:29: Cannot delete value (Spring Lake) from index d:\morph3\texis\mktDB\mkt2000014LocationCity.btr -->
<!-- 006 /texisUpdate/DelByID:30: Cannot delete value (Spring Lake) from index d:\morph3\texis\mktDB\mkt2000000LocationCity.btr -->

The records seem to be deleted fine, I just get these messages occasionally. What do they mean?

[james120]

Just wanted to mention that I just got the same error, and this was an absolutely brand-new index, and the data had not been changed afterwards at all. If John's explanation is correct, it worries me a little that the index is missing random entries for some reason. Is there anything that can be done to double-check this sort of thing?