Hi I host my website on JustHost
I have read a few threads but the problem is still remain

showthumb.php is 777
GD library is installed

my webpage djchentao.com/index.php?option=com_content&view=section&layout=blog&id=10&Itemid=60

I have changed to phoca gallery and now it works

I am also thinking of using Justhost, I hope that I won't have the problem that happened to you. I guess that if it does happen, I'll try what you suggested here, thank you.