[AccessD] OK, I have a weird one...Filter is case sensitive?

I had a user call me saying she could not find a customer when filtering by
the account number.
She was able to see the customer in another screen, so she knows it should
show up.

I asked her for the CustNo, and I filtered the datasheet sub form by right
clicking on the custno field and choosing the appropriate filter menu items.

I asked her, over the phone, to do the same.

When she still wasn't getting the expected results, I figured she was doing
something wrong and went over to her desk.

She was doing it right. I did notice that she was using lower case letters,
which shouldn't matter.

I asked her to use all caps. She did and the filter worked!

I thought, how weird.

Came back to my desk and it filters in lower case or upper case.

Is there a setting somewhere that would affect how a filter filters?

A2007 & A2010.

Thanks,
David