Help !! Can't upload any .gif, .jpg, .png images ?!?

[1000yard]

Hi,

prestashop 1.1.0.5 ...

... I cant upload any images (logo, language, products) and get always the same failure reply:
"1 error image format not recognized, allowed formats are: .gif, .jpg, .png"

Have saved my test images in .gif .jpg .png tried different software (photoshop, preview, fireworks)
and different sizes AND nothing works !

I even can't download the existing IPod images from the demo site and upload them again !?!?!

Checked all php permissions also ...

Anything else works fine, like editing new categories, products etc.

Urgent please help - what could be the problem ???

Cheers,
Born