Couple of suggestions.
Clear your browser cache, if that doesn't work make sure Javascript hasn't been accidentally disabled.
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Sat 31 Mar 2012, 17:31,
archived)
If what mofaha said has no effect,
Try switching browsers too, I had a problem of not being able to log into one site once and the hide function here refused to work, I switched browser and all was fine... something to do with cookies being nacked in my usual browser..
( ,
Sat 31 Mar 2012, 18:03,
archived)