This problem is in v 8.0, only in PL lang version, in 7.2 or 8.0 EN works fine.
When i try to create new appointment in callendar, field "reminder" has value (in english) "5,000 min before" (in attachment is 5 hours, that doesn't matter now). In other lang has "5 min before" wihout ",000".
When i delete ",000" and press save ,000 is automaticaly added and i see msg (in attachment) "You can not save. There are bugs that need to be corrected: the value of reminders is higher than the maximum value.".
This: http://bugzilla.zimbra.com/show_bug.cgi?id=69570#c16 does'n work.