MEK will do the trick, but if you're in the USA it may not be that easy to come by. And it's nasty stuff.
I've never had any real trouble cleaning up a mess with lacquer thinner, and it should do the trick in this case. It's not the nicest stuff either, but it's much more easily accessible.
With a couple days soak, a bit of prodding with a needle or long piece of stiff wire and lotsa Q-tips and pipe cleaners, (not to mention elbow grease) you'll get it clean.
Windex won't touch it, especially if it's dried. Most acrylics are impervious to any such solvents after thay have dried.
Again, lacquer thinner may not be pleasant to work with (I LUV it, though!!!
), but it, along with a bit of work and patience, will do the trick.
Fade to Black...