login encoding (problem after RC3 upgrade)

[medy]

SMF Version: SMF 1.1 RC3
Hi,

I found that members in RC3 cannot login in if their username has some special characters in it
It worked in RC2

Could you please tell me which file is associated with login page encoding? I think it is an encoding issue.
The funny thing is next: member who writes his username (with password) twice can login without problems. 

Don't know what to do Half of my forum users can't login right now 

[jerm]

Please do not double/triple post the same support question.