Crop window moves randomly

[Gordon30579245csmb]

I recently updated my Windows version of Lightroom to 6.4. Since then I have been unable to crop images because the crop windows repositions itself seemingly randomly when I attempt to position the window. Is this a known bug? Is there a workaround? The application is basically useless to me now since this began occuring.

[Gordon30579245csmb]

Update: I rebooted my computer and the problem seems to have gone away.