large images (2M) throw a non descrriptive javascript error and doesn't upload

When I try to upload a large image (I don't have the problem with small images), e.g. 2M I get a javascript error once the image is "uploaded": "An error occurred /fupload/js/image
". The display says 1 image uploaded but when going to next step it says queue is empty.

Tnx,

HnLn