Wondering what the problem is with the Digital Product download

Hi Friends ,
i am having bad problems with my zencart products downloads, when my customer purchase the product then they come to download the product file they get a error
( When I go to download the model I get an error that says that the file could not be saved because it could not be read (see attachment). What do I have to do to download this thing? )

here is the screen shot,

http://i39.tinypic.com/zl3gxv.jpg

here is the live website.

https://www.3drevolution.org

Please help me in ASAP,:(:(

Are your zip files in zencart download folder?
zip files should be named without spaces
i.e
should be heartmax.zip

yes my all files are in /downloads folder and in my zencart dwonload atributes blips are green and working fine. but any one want to download any file i got this problem

jeffhardy:

yes my all files are in /downloads folder and in my zencart dwonload atributes blips are green and working fine. but any one want to download any file i got this problem
Files should be be download folder NOT downloads
Did you rename file as per my previous post...
NO SPACES AND NO CAPITAL LETTERS..

Have you turned off GZIP compression in your ZC admin?

(Files should be be download folder NOT downloads
Did you rename file as per my previous post...
NO SPACES AND NO CAPITAL LETTERS..)

Yes my all files are in Download folder. but i have not renamed that file. but it not works with like that files 3dmodels.zip
and
i have turned on GZip Compression,

jeffhardy:

i have turned on GZip Compression,
Turn it off

i think that is work fine now but please tell me thats is still not resume supprt why.

I had an issue with downloadable products where they stopped working but had worked fine previously and a cloned store with the exact same
files and settings worked fine on a different server account.

The issue was that something about the server settings was not allowing zencart to create the temporary download folder.

It was not giving an error message though, it would just hang.

The solution was changing folder permissions on the particular folder from the previous 755 to 777

i have changed the permission Download folder but it still i have that problem :
when downloads go to 12% to 30% and stops
and when wi retart it it start from 1% and not resume support.