LyX ⇒ Windows "alt" key problem

[SFC]

I'm having a problem when inputting math into LyX using the key binding provided. For instance when I want to input a fraction I go into math mode (ctrl+M) and then try and use the fraction key bind (alt+M F). In windows however alt is the key that allows for the shortcuts to the drop down menus in most programs. This means when I go for a fraction the drop down menu for "File" pops up and I can't input anything.

This wasn't a problem before for some reason and it isn't a problem on my Linux system just Windows. The only solution I can think of is to change all my key binds but obviously this could take some time and since it once all worked I was wondering if anyone knows of a quick fix.

EDIT: Also note that other alt commands work for instance "alt+P I" for bullet points works fine