Alex Support, Jul 30 00:31 (JST):
Hello,
Thank you for contacting us. Sorry for the inconvenience happen,
On time being we have an technical issue on btc withdrawal that appearing on block chain, by the same our developer team is working on it for fixing-up. mean-while please let us know if your transaction got processed.
Best regards,
Mt.Gox Team
https://www.mtgox.com