Web Login/Manager Login wierdness

I’ve never used the "security code" image in any of my sites before, so I’m not sure if this is something very old or what exactly it is.

The manager login uses the security code image. If I’m logged in as a manager user, then try to log in to a WebLogin form, I get a message that I didn’t enter the correct security code. Plus I’m now no longer logged in to the Manager and have to log in again.