Foxit error message while trying to download a huge file

I am getting a strange error when I tried to download a . PDF file from Foxit.
I have pasted a copy of the error message below, for your reference.
Format error: not a PDF or corrupted.
I am trying to download a huge .PDF file, which comes up with this error message. I am using my Window Vista Ultimate machine to download this file. When I start the download, it starts downloading normally but after it reaches more than 1 MB it starts slowing down and gives me this error message.
This is the first time I am trying to download it on my Vista machine.
Is this something to do with the OS and its security features?
Since I was able to download it previously on my Windows XP machine .
Please help.
