I know my Apple ID & Password and they both work for every purpose on my iMac except the lock screen. If I swipe my mouse in a certain way (and I'm not exactly sure which mouse gesture it is) but it locks my screen and demands a password be entered to unlock it. However, it doesn't accept my normal Apple password, the same password I use to install things or for purchases etc. I have to do a hard reboot and it logs on as normal. I would appreciate any help with this.