natted ftp connections stop halfway through

[stooo]

I have a strange problem ftping some files out to external servers

The file is a text file, generated by another application, and as around 100k in size. the only thing special about the file is that it contains loads of spaces.

On trying to upload this file, it gets about halfway, and then stops for a few minutes before (usually) finishing

I can ftp other text files of around the same size with no problems.

The problem only occurs where NAT is involved (I can send it to sites across vpn where no nat is involved without any problems)

If I do a fine/replace of the file, and replace every 10 spaces with 1 space, I can ftp it without problem.

My logs don't show anything, so I am a bit stumped.. can anyone hlep?

Running Checkpoint NG FP3 on a Nokia IP330 IPSO 3.71

Thanks