This happens quite frequently (not sure exactly what triggers it though)! Consider this: #ifdef SOME_DEFINE
DoStuff();
#endif
foo(x);
bar(y);
baz(z);
If I edit some stuff inside the ifdef-clause, all code below the #endif-statement is grayed out! Re-parsing or re-opening the document does not help. It seems you simply have to wait a minute or so, to get your syntax colors back. Frustration? LOL :)