Some keyboard keys not working on password input to Yosemite login screen As stated in the title some keys don't work when trying to input my password into the Yosemite login screen. The weird thing is that if my mouse isn't plugged in (Razer Naga) when I turn on my Macbook Pro the issue doesn't occur and if I restart my Macbook Pro, even with the mouse plugged in, then everything works as expected. Anytime the Mac is restarted in the keyboard works as expected on the login screen but when powering the Mac on it doesn't.

I have done an SMC reset to no avail. I never had this problem in any previous versions of OS X.

UPDATE:
I started plugging my Razer mouse into a monitor stand with a built-in USB hub and now the problem almost never happens... it still does occur, but probably only 10-20% of the time as opposed to 100% when the mouse was plugged in directly to the Macbook on startup.
The fact that the keyboard works at the boot screen before user level code runs is curious.

I wonder if one of the kernel extensions or control panels that customize that keyboard are causing issues. As I don't have that hardware, it's hard to poke and see what files might be causing the issue.

You can try several things to corner this:


Make a new user account and turn off auto log in in the Users preference pane
You could hold shift down when booting to rebuild all kernel extensions and then log in safely without most third party apps running
You could uninstall any drivers and/or open a support ticket with the vendor


In each of the above cases, you can test logging in to the new account / safe boot system and see which are broken and which are working. Worst case, edit the question and/or open a new question with the details of this triage.