It may not be photo bucket. I also have Norton and it is good virus protection however my computer was acting the same way yours is and was infected by malware (I think it came from the board here when I downloaded a "viewer"). After spending $100 on software to clean my files, I found this free version that worked well on my other computer.
http://www.malwarebytes.org/products/malwarebytes_free/
Hope this helps.
Linda