I just receive (on both) the following which is ok!:
Jan 18 19:32:55 ns1 named: client 188.8.131.52#27245: query (cache) 'www.xxx.eu/A/IN' denied
problem seems getting bigger! can't ping to ns1.codag.net, ns2.codag.net anymore! i sent an email to switch where i registred these nameservers. could it be an issue on side of switch.ch?