E6410 asking for preboot password when i haven't even set one!

I have a Dell E6410. I went to bios to change boot settings and when i went to change them back after few minutes, it was asking for preboot password OR fingeprint authentication. I have never set any bios/preboot passwords, but i have set fingerprint authentication to windows 7. I was able to authenticate myself using fingerprint to access bios. How did this happen? To get the preboot authentication off, i would need to type a password, when i only have a fingerprint. I tried the TPM password, which is the only password i have ever set for this laptop, and it didn't work for the preboot. What should i do? I can access windows still through F12 boot menu. Very weird and annoying... I haven't even set the password. No one has!

EDIT:

Solved by ways that are not probably approved by Dell, but... At least i got rid of the password that appeared out of nowhere! Sure it worked before, but it would've been interesting if i had cut off my middle finger (Again... I didn't pick which finger it decided to use for authentication.) with circular saw... Or something less dramatic happened to my only authentication method...

But the solution is to contact Dell support for new system password if you're able to prove the ownership of your laptop. Or wherever you decide to get it from... And press Ctrl-Enter after typing in the password in PBA window on boot. It should remove the password and the PBA (Pre-Boot Authentication).