Czech version is causing very fatal error, making it impossible to enter any correct date of any date and year in Jun and July. Unfortunately, no one is responding to my contact form, so I am trying to communicate this way. Could someone start to solve this problem?

 Attached see the screen shot of error which occures every time the time entering dialog is called.

 PS: as I am beeing software professional, I do know the problem a can give some advices how to solve it if somebody cares about.