Some Keyboard shortcuts don't work under Lyx 1.3.6 (Windows)

[Wang Xiangqi]

I am not sure whether I need special setting or not, but some keyboard  
shortcuts don't work under LyX 1.3.6 (Windows). Like Ctrl+M (math),  
ctrl+enter (forced new line), ctrl+l (latex),etc.

Anyone can shade some lights on it?
More thanks.

Regards.

Sunkey