Strange Login Problem

[rrrhre2s]

Having a strange problem with login, I am logged in and follow a link to another post am asked to login again, re-enter password and user name it always fails the first time with an invalid password or user name. Enter the same thing again an I am logged in successfully. Though I was mistyping but tried copy and paste and the first try always fails but second attempt is successful.

Any Ideas ?

rrrhre2s