Serious problem with downloaded files

I used the smallerik file browser plugin and it worked fine until I realised i had a problem when I downloaded the files.
Although, download seems to work fine when I try to open the file (any kind of file… pdf, word, excel… etc) it doesn’t open because (as it says) it is corrupted.
When I opened the files useing a notepad I saw that in the beggining they all started with the HTML code from my web site. In fact, they all include the HTML almost up to the point where the link of the file is.
I also downloaded the files trhough FTP and they worked fine.
So i assume there is a problem in the function for downloading files.
Is there any setting that I miss? or is it a bug?
Can you help me?

http://wordpress.org/extend/plugins/smallerik-file-browser/