See also Language Log's take. Basically, even popular industry-standard implementations of grammar checking are, in reality, worse than useless.

Out of interest, what were your "two (or possibly four) grammatical solecisms" in your first sentence? The only possibility I can spot is the singular/plural mismatch of "a mechanism" vs. "these are", and even that's stretching a point. But maybe I've been reading too much 18th-century literature. :)