"Invalid signature detected. Check Secure Boot Policy in Setup." I've been fooling around with some live CDs on my Surface Pro 1, and now when booting back to Windows I receive this error at boot. It seems to be a common problem however I have yet to resolve it. I've tried disabling and enabling TPM and secure boot, and enabling and disabling keys. If anybody has a suggestion, or can point me in the right direction, that would be appreciated. Additionally, I have some unwanted entries in my UEFI boot loader that I would like to get rid of, as well. This may be part of the problem. Thanks in advance.