Can connect to localhost, but not 127.0.0.1.
Let me know if you need more system info.

// work

alexander@k226741:~$ mongo localhost:127017
MongoDB shell version: 0.9.7
url: localhost:127017
connecting to: localhost:127017
type "help" for help
> exit
bye

// don't work

alexander@k226741:~$ mongo 127.0.0.1:127017
terminate called after throwing an instance of 'boost::filesystem::filesystem_error'
what(): boost::filesystem::path: invalid name "127.0.0.1:127017" in path: "127.0.0.1:127017"
Mon Aug 10 14:04:30 mongo got signal 6 (Aborted), stack trace:
Mon Aug 10 14:04:30 0x411912 0x2aaaab6b3100 0x2aaaab6b3095 0x2aaaab6b4af0 0x2aaaaafac0e4 0x2aaaaafaa076 0x2aaaaafaa0a3 0x2aaaaafaa18a 0x470083 0x470911 0x412b0a 0x2aaaab69f1c4 0x411359
mongo(_Z12quitAbruptlyi+0x3c2) [0x411912]
/lib/libc.so.6 [0x2aaaab6b3100]
/lib/libc.so.6(gsignal+0x35) [0x2aaaab6b3095]
/lib/libc.so.6(abort+0x110) [0x2aaaab6b4af0]
/usr/lib/libstdc++.so.6(ZN9gnu_cxx27_verbose_terminate_handlerEv+0x114) [0x2aaaaafac0e4]
/usr/lib/libstdc++.so.6 [0x2aaaaafaa076]
/usr/lib/libstdc++.so.6 [0x2aaaaafaa0a3]
/usr/lib/libstdc++.so.6 [0x2aaaaafaa18a]
mongo [0x470083]
mongo [0x470911]
mongo [0x412b0a]
/lib/libc.so.6(__libc_start_main+0xf4) [0x2aaaab69f1c4]
mongo(__gxx_personality_v0+0x239) [0x411359]