Have you ever faced this problem? I actually did once. For quite a sometime, I thought the problem is with my Browser so I uninstall it completely and reinstall along with Google toolbar. But this did not solve my problem. I Googled for my problem and found just a few questions on forums related to this problem but none of them was properly answered.
Whenever I used to hover my mouse on the PageRank toolbar, it shows no page rank information available. After browsing through 100 different sites, I found it has to do something with browser history setting.
I use Firefox, just went to the Tools> Option > Privacy and changed my setting from never remember history to remember history and it started working.
If you are one of those facing issue with this, try resolving as suggested above. I am not aware, if there are other conditions too that prevents this link juice measuring tool to stop functioning.
Please share if you are aware of the other conditions as well.
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