Server closed connection ?

Hello,
I've always used smartftp , but now since like 2 days ago I am having some problems, when I connect to my ftp and I try to open a folder or download or upload a file the ftp will close my conexion and there will be a small white circle with a red X in the folder I tried to open and it will disconnect me "Server closed connection" , I dont know if is a hosting problem or smartftp problem , if I do f5 a couple of times it will conect fine for some time.
Why is this =( ?

Here is the log:

[12:47:19] 200 NOOP command successful
[12:47:50] NOOP
[12:47:50] 200 NOOP command successful
[12:48:21] NOOP
[12:48:21] 200 NOOP command successful
[12:48:41] CWD /course
[12:48:41] 250 CWD command successful
[12:48:41] PWD
[12:48:42] 257 "/course" is current directory.
[12:48:42] PORT 133,200,4,50,14,134
[12:48:42] 200 PORT command successful
[12:48:42] LIST -aL
[12:48:43] 150 Opening ASCII mode data connection for file list
[12:48:43] Server closed connection