Hi There,
I recently upgraded to ZC v1.50 and just installed image handler 4 too.
I am currently encountering an error when I set 'IH resize images' to 'yes', it causes all my products under my various categories (suits, shirts, ties etc) to no longer show.
I used to have IH 3 installed on my old ZC 1.3.9h (before I upgraded to 1.5) but performed a fresh install upon upgrading to ZC 1.5.

I have no idea why this happens, but I know that when I then set 'IH resize images' to 'no' the problem dissapears.
I would greatly appreciate anyone's help!

Thanks