I had the same problem at a time with the word SELECT. I never got this working for WordPress and rephrased the sentence; and the bug I submitted got flagged as false alarm, on grounds it was a server problem rather than a wordpress problem.
When I bumped into the same problem with another tool, I found the following: When I send a few keywords to my server via a GET request, it savagely produced errors; and for some reason, doing the same thing via the POST method will fix this. Since then, I no longer use GET requests for updates (I believe there are a couple of those in WP) and everything works fine. Might work for you too.