Thumbnail can’t be created for photo

Hello folks,
I have a problem uploading one photo in this site. I keep getting the same error message when I try to add it to my gallery.
This is a screenshot of the error message dialog box.

Error:
Error
SN(8363-D94F-2037-5DD0) has been activated. (Error code:11)
I never had this problem before. In fact, I have uploaded images to my gallery and to the topic threads numerous times. There must be a reason why the thumbnail couldn't be created. What do I need to do?
Please help me.
Thanks!
