Target=(_blank) lost when page is saved more than once

Using: Drupal 7.20, with CKEditor 7.x-1.9, and IMCE 7x-1.7

Can create a link to a PDF and set the target to open in a new window, and it will save correctly once. However, if the page is modified and saved again, the previously linked PDF will no longer open in a new window - it will open in the same window. This happens with all of the linked files on the page, so if there are 15 links, all 15 lose their "open in new window" attribute.

I'm not sure if this should be posted in the IMCE or CKEditor project, but since it seems related more to the "open in new window" tab, I am posting it here to start with.

Thanks in advance,
Bill