on and off again problem with webpages

Hi-

I am getting the following stuff at the top of my pages at my website
at an on and off basis. Happens on my computer... doesn't happen on someone elses I tried. The .gif at the end of the string is where it always stops. Usually happens when I am into the site a couple of pages, then it appears on every page. Anyone know what's causing this? Thanks in advance.

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