Cassie from the Google AdWords team confirmed in a few Google AdWords Help threads that there is a known issue with the keyword status field in your AdWords report. In short, it might not be showing the right or most accurate status.
There are no known issues with the keyword status right now.
This status on the keyword level does not necessarily mean that the keyword is not running (especially if you are getting impressions on that keyword); rather, that you may have another similar keyword in your account that would win out in that theoretical auction instead. This may happen if you have duplicate keywords, including plurals or misspellings that are interchangeable, or if you have the same keyword in different match types but are bidding higher (or have a better quality score) on a different match type version of that keyword.
So keep this in mind if you seem surprised by any of the keyword status responses in your AdWords report.
I am not sure if there is an ETA to fixing the known issue or not.
Forum discussion at Google AdWords Help.