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Had older version may have thrown away something important. Downloaded new Firefox when I try to open it, it says a copy of Firefox is already running and nothing happens.

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Accidentally deleted some aspect of older Firefox, when I try to open new version it says there is a copy of firefox already open.

Accidentally deleted some aspect of older Firefox, when I try to open new version it says there is a copy of firefox already open.

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I have the same problem, I use Windows Vista