The good news is that this problem probably won’t have much impact on businesses, since it only occurs with the Starter Edition of Office 2010. This is a limited edition of Office that came free with many PCs. The bad news is that update KB2589275 causes the Starter applications to lose their file associations, so that users can no longer open files by double clicking them. The other good news is that you can fix it – without having to wait for another update.
Read more here:
http://www.gfi.com/blog/play-it-again-microsoft-yet-another-patch-problem-rears-its-head/