Upload asset failed to open stream: Invalid argument When I try to upload an image, I am getting the following error:

imagepng(C:/wamp/craft/storage/runtime/temp/assets53ebcb012cffa3.92019251-temp.png): failed to open stream: Invalid argument (C:\wamp\craft\app\vendor\imagine\imagine\lib\Imagine\Gd\Image.php:691)

Do you know what is going wrong?
I'd check the permissions and make sure that Craft has write permissions to the craft/storage folder first.