Yubico Forum

I have become locked out of my own personal Windows 7 PC. I have 2 Yubikey Neo which were working for a few weeks. When I attempt to log-in now, the green light goes solid and I get "Yubikey logon failed, please insert correct yubikey". I haven't changed either key. I've tried both keys and all USB ports. It happens in safe mode as well. I've re-done the challenge response settings several times and tested on other PCs and with keepass and both keys work fine. I have tried every mode through Neo manager. It seems likely to be a driver issue I am running into, though I do not know when it started or why. The challenge response is set as HMAC SH1 variable input and slot 2.

I have a backup from two weeks ago before the issue began. I'd rather not lose the work though. Any suggestions?

EDIT: To bypass yubikey authenticator, it was only necessary to rename "YubiClientAPI.dll" in C:\Program Files\Yubico\Yubikey Client API\Bin\x64 to "YubiClientAPI.dll.bak" after using a boot cd. Only encryption would prevent someone with physical access from doing this and there is really little point without encryption for local multifactor authentification. After logging in, I found that one of the drivers for the yubikey was showing as "Unknown device" in the device manager. I ran sfc /scannow to check files which corrected some corrupt system files that led to the driver issue.