Append Table Problem - Slightly Different

Hi all:
My problem is a little different than the earlier append table post.

I have T1 with an autonum field as the primary key, and T2 with
identical fields as the first, but no autonum. Usually when I append
the records from T2 into T1 all the records are appended and assigned
new autonums. Today I am getting a key violation error and only some
of the records are appending. For example, I have 231 recs in T2, and
the message I get reads like this: MS Access can't append all the recs
in the query: it did not append 49 recs due to key violations. I am
working in the query design view, not in the code.

However, and this is the source of my confusion, if I run it again, it
appends additional records while still giving me the error message,
but a different # of recs that cannot be appended. And again, and
again, until as of this moment I've run it about 10 times, and now
only 52 records remain that are not appended. I'm very concerned that
my database is corrupt or something major is wrong with my program.
I'm running Access 2003 sp2.

Has anyone else experienced anything like this? Or does anyone know
how to possibly fix it?

TIA.
Fily