out of the blue (last night)
What changed? What versions of OS, Java, and SQL Developer are you using? More recent queries along this line are related to msvcr100.dll, not msvcr71.dll. It looks like you are lagging a bit on some upgrade cycles and something got out of synch after an update.
Here are a couple of discussion, one from over 5 years ago (for msvcr71), and another more recent one (for msvcr100)...