f you cant download try a different browser. May be that helps?

I had a similiar problem on patch day. This solution is from my memory (Windows XP service Pack3):

After downloading the manual patch i got a new error. The manual patch didnt work I deleted Navyfield as recommended in the general technical solution thread. As there mentioned i deleted the registry entries for SDEnternet and Navyfield. I also deleted the EnFunsUpdater manually by deleting the files on the harddisk. What helped me was to delete all other, additional registry entries and keys with the string "navyfield". Use the search function of regedit for it. There were dozens of additional nf registry tags, for example for the soviet sprite package. Most of them were subkeys of a key called "Protected". Be careful doing that, you dont need to kill the protocol feature of the registry protocolling your file manager and web browser activity if there is just at that moment a key with "nf" string in that protocol. After installing the fresh downloaded full client 1323 version the updater downloaded the needed files for the last patch (also 1323 - it is a bit strange), but failed to start nf or produced a file error the internal file check says at the login screen. Just let the updater download the files and close it normally. Start it again and wait a moment, it will not download again. Click start game, at that waiting time HS seems to update itself or check something, after that NF will start normally and worked fine.

Edit says: After uninstall reboot your pc. After cleaning the registry reboot your pc. Better reboot 1 time more then necessary. Then install the new version.
Edit2 says: I choose a different directory name for the new version, despite the old stuff was deleted. But by doing that old registry keys or something else deep in your system still alive and pointing to your old navyfield would point into void and installer programm would be forced to set up new pointers.