See here:
Hi,
Já vi virus causando isso, como está acontecendo no provedor, trata-se de um virus nos servidores do provedor. I have seen virus causing it, as is happening in the provider, it is a virus on the servers of the provider.
O problema é que nunca admitem, se pelo menos resolverem, ótimo, do contrário o jeito é trocar de provedor. The problem is that they never admit, at least resolve, great, otherwise we'll just switch to another provider.
http://translate.google.com/translat...ial%26hs%3DQ0O
Providers try to push the blame on you (saying it is flawed for its application), but if your application is not capable of uploading files, it is virtually impossible to modify the files in your application - to change, your ISP also has a much great fault.
Also, it might be a hole in your application. Is it online now?