I tried the searching and went through http://wordpress.org/support/topic/164999?replies=1
When I try to upload images, I receive the following warnings:
Warning: imagepng(): Unable to access /home/www/xxxxxxx/content/wp-content/uploads/2008/08/image11-100x100.png in /home/www/xxxxxxx/content/wp-includes/media.php on line 239 Warning: imagepng(): Invalid filename '/home/www/xxxxxxx/content/wp-content/uploads/2008/08/image11-100x100.png' in /home/www/xxxxxxx/content/wp-includes/media.php on line 239
My image gets uploaded just fine, but the thumbnails are not being created. I am not really sure what the "unable to access" warning means. My images show up in media/image galleries and I am able to use them in posts. But thumbnails are no being created.