Extension Manager won't open

Hello all. It hasn't really been a problem so far, but ever since I upgraded to DW8 (last summer) my extension manager doesn't work. If you try to open it, it comes up in my task bar, but it's not visible anywhere on the screen. It's like it opens to left of my screen and I can't get it over here where I can see it. If I right-click on it in the task bar and choose size or move, my mouse turns into that 4-point arrow thing and goes all the way to the left edge of the screen, but if I try to move or resize it, nothing happens.

So, I'd like to know if anyone knows how to fix this, or where I can go to download the extension manager to reinstall it.

Thanks!