Wait, what? Why didn't you let it re-map? Well, actually, I'm not sure if deleting your fsx.CFG resets your keyboard mappings, so maybe it isn't a problem.
Anyways, instead of deleting it, I'd recommend copying the contents of the [Trusted] section of your fsx.CFG to another file and saving it (as a backup), then removing it from the fsx.CFG.
What's in that section, I believe, are C++ gauges, and I'm not completely sure, but also things that load alongside FSX (stuff in the exe.xml and dll.xml files). I believe, if a C++ gauge or .dll based addon crashes, it can bring down all of FSX with it - reason being that the SDK states "The recommended method of writing an add-on is to build it out-of-process, as an application (an .exe file) rather than in-process, as a library (a .dll file). This is because out-of-process applications provide more stability, if they crash they will typically will not crash Flight Simulator..."