New Post: cannot download attachments files of a product

hi to all and thanks for your replies.
i added files to my product but cannot download them, get error page.
link to my site: http://lbltradingv2.allbiz.org.il/Catalog/tabid/105/ProdID/4/CatID/3/language/en-US/Default.aspx

the error:
500 - Internal server error.
There is a problem with the resource you are looking for, and it cannot be displayed.

any ideas

thanks in advancd