I think I may have the same problem.
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I'm running OpenLP 2.0.3 on a Mac OS X Mavericks. Everything was fine and working well for several weeks. Then suddenly I found that I couldn't 'open' the Songs plugin in Media Manager. Its completely unresponsive when clicked on.
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Investigating further, I have found that the problem affects whatever is the top plugin in the list. For example, if I disable the Songs plugin and then re-enable it, it suddenly works again but has been repositioned at the bottom. Now whatever it at the top of the media manager list has stopped working!
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I have tried re-installing OpenLP but it hasn't made any difference.
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I haven't seen this problem when using the windows version. Hoping someone can throw some light on how to fix this.
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Howard.