ACZoom

Not clear what is hanging - what do you mean by "session is hanging"?
If it is your FTP client, then it is likely related to something in VSFTPD itself, you may need to try their mailing lists for help, check up your DNS and reverse-DNS issues on your system, etc.

As for blockhosts, is there a specific reason you need to match the line you listed? Does it not print the following line in your logs:
Fri Jan 21 15:56:57 2005 [pid 6726] [test] FAIL LOGIN: Client "10.204.30.15"
The above line is already matched by the default rules in blockhosts.py

If you need to debug blockhosts, you can run it with the debug option, to see what it matched.