Error 553 uploading to site

I have just installed SmartFTP and have a hosting with fasthosts.co.uk. I am able to connect to the ftp site however when I try and upload i get the following error messages:

553-Can't open that file: Invalid argument
553 Rename/move failure: No such file or directory

I have tried manually uploading by entering ftp from the cmd prompt. I have used the put command and get the same error message there.

Any idea what is wrong?

Please post the whole log from the beginning (so we can see which server software is used) as well as your SmartFTP version information (Help -> About -> System Information).

Here is the contents of the log:

[20050816 11:47:18] Log opened
[20050816 11:47:18] SmartFTP v1.5.989.0
[20050816 11:47:18] Resolving host name "ftp.myweb.com"
[20050816 11:47:18] Connecting to 213.171.193.5 Port: 21
[20050816 11:47:18] Connected to ftp.myweb.com.
[20050816 11:47:18] 220-Matrix FTP server ready.
[20050816 11:47:18] 220-This is a private system - No anonymous login
[20050816 11:47:18] 220 Please note: files for your website must be stored under the htdocs directory.
[20050816 11:47:18] USER myuser
[20050816 11:47:18] 331 User myuser OK. Password required
[20050816 11:47:18] PASS (hidden)
[20050816 11:47:18] 230 OK. Current directory is /
[20050816 11:47:18] SYST
[20050816 11:47:18] 215 UNIX Type: L8
[20050816 11:47:18] FEAT
[20050816 11:47:18] 211-Extensions supported:
[20050816 11:47:18] EPRT
[20050816 11:47:18] IDLE
[20050816 11:47:18] MDTM
[20050816 11:47:18] SIZE
[20050816 11:47:18] REST STREAM
[20050816 11:47:18] MLST type*;size*;sizd*;modify*;UNIX.mode*;UNIX.uid*;UNIX.gid*;unique*;
[20050816 11:47:18] MLSD
[20050816 11:47:18] ESTP
[20050816 11:47:18] PASV
[20050816 11:47:18] EPSV
[20050816 11:47:18] SPSV
[20050816 11:47:18] ESTA
[20050816 11:47:18] 211 End.
[20050816 11:47:18] Detected Server Software: PureFTPd
[20050816 11:47:18] PWD
[20050816 11:47:18] 257 "/" is your current location
[20050816 11:47:49] CWD /htdocs
[20050816 11:47:49] 250 OK. Current directory is /htdocs
[20050816 11:47:49] PWD
[20050816 11:47:49] 257 "/htdocs" is your current location
[20050816 11:47:49] Remote file exist check: 'index.htm'.
[20050816 11:47:49] SIZE index.htm
[20050816 11:47:49] 550 Can't check for file existence
[20050816 11:47:49] TYPE I
[20050816 11:47:49] 200 TYPE is now 8-bit binary
[20050816 11:47:49] PASV
[20050816 11:47:49] 227 Entering Passive Mode (213,171,193,5,104,32)
[20050816 11:47:49] Opening data connection to 213.171.193.5 Port: 26656
[20050816 11:47:49] STOR index.htm
[20050816 11:47:49] 553-Can't open that file: Invalid argument
[20050816 11:47:49] 553 Rename/move failure: No such file or directory
[20050816 11:47:49] PASV
[20050816 11:47:49] 227 Entering Passive Mode (213,171,193,5,31,92)
[20050816 11:47:49] Opening data connection to 213.171.193.5 Port: 8028
[20050816 11:47:49] MLSD
[20050816 11:47:49] 150 Accepted data connection
[20050816 11:47:49] 227 bytes transferred. (1.47 KB/s) (150 ms)
[20050816 11:47:49] 226-ASCII
[20050816 11:47:49] 226-Options: -a -l
[20050816 11:47:49] 226 2 matches total
[20050816 11:47:49] Transfer failed.
[20050816 11:47:59] Log closed