Can log in on home network, not from work...

I have FTP working at home, I can browse via SmartFTP client from any pc on my home network (Vista or XP OS's) yet when I try to log in from work, I cannot access the files. This is the log file that I get:


[09:27:59] SmartFTP v2.5.1006.46
[09:27:59] Resolving host name "69.145.99.171"
[09:27:59] Connecting to 69.145.99.171 Port: 21
[09:27:59] Connected to 69.145.99.171.
[09:27:59] 220 Microsoft FTP Service
[09:27:59] USER anonymous
[09:27:59] 331 Anonymous access allowed, send identity (e-mail name) as password.
[09:27:59] PASS (hidden)
[09:27:59] 230 Anonymous user logged in.
[09:27:59] SYST
[09:27:59] 215 Windows_NT
[09:27:59] Detected Server Type: Windows NT
[09:27:59] FEAT
[09:27:59] 211-Extended features supported:
[09:27:59] SIZE
[09:27:59] MDTM
[09:27:59] 211 END
[09:27:59] TYPE I
[09:28:00] 200 Type set to I.
[09:28:00] REST 0
[09:28:00] 350 Restarting at 0.
[09:28:00] PWD
[09:28:00] 257 "/" is current directory.
[09:28:00] TYPE A
[09:28:00] 200 Type set to A.
[09:28:00] PASV
[09:28:01] An established connection was aborted by the software in your host machine.
[09:28:01] Server closed connection


Sometimes it appear that I am logged in and it just ends with '257 "/" is current directory.' but I cannot see the file structure at all. It also gives this message when I let the client sit idle...:

[09:33:49] NOOP
[09:33:49] 200 NOOP command successful.
[09:34:20] NOOP
[09:34:20] 200 NOOP command successful.


Any ideas? I have tried everything I can think of to no avail.