"P"key in the USB keyboard refuses to work

Only the "P" key on my Apple USB keyboard (MB110BE / B) doesn't works.

Or better; works only at the FIRST TIME IT IS CONNECTED TO THE USB PORT.

Then, returns to not respond, neither in caps lock.

When I use the keyboard viewer, the "P" key doesn't responds.

From what I understand, the key physically works, but it isn't recognized by OS X.

My other Bluethoot keyboard works normally.

Sugestions?

Tks,

Saulo