Dell Inspiron 3148 F10 key alternative function??

Hi, we had a problem with this notebook - keys on the left side on keyboard sometimes didn't work.

After factory reset it seems that the problem disappered, bud during testing I have noticed, that the altrenative function of the key F10 is typing the letter Y (when i'm in notepad, when i'm in metro start it doesent do anything till i start searching - then i can see typing Y again.

As a F10 key - it works, as a alternative function - what is the purpose of this key? is it normal that it is type the letter Y or it's something to start a reclamation?

I'm with just installed Win8.1 from recovery, original Dell, nothing else.

Can anybody help with my questions?

Thank you