keyboard shortcuts for undo and redo stopped working

hi everyone,

Grasshopper suddenly decided to not allow me to undo using the keyboard shortcuts ctrl+z, if I press ctrl+z in grasshopper now i'll activite the rhino command line instead of undo the last thing I did in grasshopper. If I go to the edit menu and click on undo it still works. I noticed that under the edit menu, undo and redo no longer have 'Ctrl+Z' and 'Ctrl+Y' texts next to it, as the screen capture I uploaded shows.

I tried uninstall and reinstall but the problem is still there.

I searched using some keywords but didn't find a previous discussion on this. Anyone having same problems?Thanks.

Alex