MDL Extension Suddenly Not Playing Back

Hi all,

I've been working on a medley of The Planets by Gustav Holst for DCI band (I know this has already done but I want to make it better). Anyhow, it said to me that there was an error in the score with staves 40 and 42 I believe: "expected: 5/4; result: 3/4."

And when I went to fix this, the MDL extension just stopped working for this particular score. as well as in general on any other score.

I even tried uninstalling and reinstalling, but to no avail.

Does anyone have any idea as to why that might be?--And, more importantly, how I might fix this?