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Go to ~/Library/Safari and copy the Downloads.plist file to the Desktop and move the file in the Safari folder to the Trash and relaunch Safari. If you still have problems with downloading files...

Go to ~/Library/Preferences and copy the com.apple.safari.plist to the Desktop and then move the com.apple.safari.plist to the Trash. Relaunch Safari.

In Safari Preferences/General, do you have the box 'Open Safe Files after Downloading' ticked?

Try UNticking that and restart Safari.

Maybe one of these will work.
 
Have you tested in another user account? If it happens in another account, you will likely need to reinstall Safari from your install disc. You can download Firefox or another browser on a different Mac and copy the DMG to a CD. You really should also consider picking up an external drive for Time Machine or whatever backup method you prefer.
 
I dont have another mac.

If using another account works, then what should I do cause it would get very annoying to have to go to another account just to download zip files cause they take forever (1 .zip file, 250MB, is taking 3hrs. and 30 mins) right now.
 
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