cfimage not working with large files

I have been experiencing some weird behavior with cfimage and am hoping someone can provide some insight on what to do.

I have an application where a user can upload an image, and I am using cfimage to create a thumbnail. However, when the source image is large (testing shows around 5 MB is where I start having problems), the thumbnail never gets completely created and the partial file that is created cannot be deleted without a reboot.

Has anyone else run into this?