This is the Windows firewall blocking Java 7 when it sees these commands sent on a socket. Normally, the Windows firewall prompts to add a newly installed program. But in this case it doesn't seem to happen - we aren't sure why.
User, yetikov, on the Netbeans forum reports that the following command will fix the problem:
Code:netsh advfirewall set global StatefulFTP disable
We have also had a report that ZoneAlarm can cause this problem - again, it did not prompt to stop blocking.
A bug report has been submitted to Sun/Oracle - http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7077696
You can help bring attention to the problem by voting it up here.