Problem with Photobucket


Recently, I've posted a new batch of icons in my graphics community. I've uploaded all the images with my account in Photobucket.
Everything was fine until yesterday, when I realized that some of my icons suddenly lost their quality. They were OK some days ago,
but now they are damaged. Compare:


                    
        ORIGINAL                                      DAMAGED BY                
IT WAS SUPPOSED                              
PHOTOBUCKET
TO BE LIKE THIS.                               AFTER SOME TIME.                
                                   

Does anybody know the cause of this? Is there any way I can recover the original quality?
I don't want to upload my icons in another site...
If I can't recover the original quality in Photobucket, I'll have lost some of my icons, since
I deleted all them from my PC.

I am glad for any help.

EDIT: OK, this is really strange,but when I posted the Photobucket link here, all the icons went
           back to normal. ?? How can something like this happen? This is driving me crazy...

SOLVED. Thank you very much to jadeleopard , canuck_kat  and ina_ami for the help!