>var n = Math.floor(Math.random() * 77777777777) + 1;
this is just adding a random querystring to the end of the image src so your browser won't use it's local cache.
This is working. Kudos to the codefag that figured it out. Doesn't work for .PNG, which tells me that Jim++ don't store all images in the same spot? Remonds me of the hover issue we used to see only with .PNG's.