I haven't heard of this issue before. You might try redownloading it. If you have anti-virus, that might be affecting it as well. AVG dislikes Unity games quite a bit.
This may be a solution, I do use AVG. I also tried reinstalling it, but the issue kept happening.
By the way, I sent an email to the support in case you don't see my comment here, but since I saw your reply you can ignore the mail.
