I had this problem before you need to clean keyboard if it didn't help then you need to replace it
[https://www.youtube.com/watch?v=dAfYTzLKLJY|Try this tutorial]
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=== Update (04/27/2016) ===
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You said keyboard works with notepad without problems so I would suggest to check your language and region settings delete all selected languages and regions and make sure to select only English then test keyboard.
I had this problem before you need to clean keyboard if it didn't help then you need to replace it
[https://www.youtube.com/watch?v=dAfYTzLKLJY|Try this tutorial]