It could be that the 'History' window is rendering off-screen.
The 'History' window takes focus when accessed and requires user intervention to close the window. Without access to the window so as to provide such intervention, it would give the impression that Moneydance had frozen.
Go to the 'Securities Detail' section of an investment account and call up the 'History' window (Moneydance will appear to have frozen).
At this point, use key-combo ALT-SPACEBAR (a small context menu may or may not appear at the edge of your monitor).
Tap the letter 'M' on your keyboard to invoke the 'Move' command.
Using your keyboard's ARROW keys (likely the LEFT ARROW key) try to move the orphaned window back on-screen.