A little more information, please.
What, specifically, happens when you attempt to download a file? Please give an example or two, including website addresses from which you're attempting to download and the complete text of any error message.
Can you "surf the web" with the problem computer? That is, can you visit websites even if you can't download files?
What browser are you using, e.g., Internet Explorer, Firefox, Google Chrome, something else?
Click Start, right click "Computer" and select "Properties," then answer the following questions based on the information displayed:
- What edition of Windows 7 is installed?
- Is Service Pack 1 installed?
- What is the "System type" (in the "System" section at about the middle of the screen)?
- What is shown under "Windows activation" at the bottom of the screen?
Open Device Manager (click Start, type Device Manager in the Search box, and press Enter)
- Please list all items, if any, that show a warning icon
- Double-click "Network adapters" and please list all items in this category; if any item in this category shows a warning icon, double-click that item and report its complete name and its "Device status"