[Plugin: CW Image Optimizer] Unsupported file typeMetadata is missing file path

I am on a CentOS 5.8 (64bit)
and installed the related dependencies:
x86-64: https://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el5.rf.x86_64.rpm

littleutils is installed correctly and everything works great for JPGs and GIFs but with PNGs:

1- with “cw-image-optimizer” enabled I upload any kind of png and I get:
Unsupported file typeMetadata is missing file path

2- with the plugin disabled, I upload successfully the pngs then I activate the plugin and bulk optimize the images and the server crash I get Internal error (white page)

is this a bug in the plugin? or can it be fixed at plugin level?

What it really bothers me is that it was working ok (even the pngs) for quite awhile….

Can this be related to CentOS upgrades?

I even reinstalled the server from scratch but I get the same behaviours even if “cw-image-optimizer” is the only active plugin in wordpress.

I am on Debian and I am getting the same error message. I uploaded a new png file but gives me the error:

Unsupported file typeMetadata is missing file path.

I know littleutils is installed properly as I used it from the command line. Any help would be appreciated.