If you did a manual install meanin you copied and pasted the files over instead of doing how you would normally do it when installing the thread below should help you!
I now remember when i did a manual install a few times i had to do whats stated in link below!It should work after that cause it worked for me!
https://activision.custhelp.com/cgi-...i=&p_topview=1
or just read below in the thread were replying to!
If you performed a manual install of the game you will need to do the following.
This answer is for an Advanced user. Please do not attempt the below solution if you are not comfortable editing the Registry. Damaging the Registry could result in very adverse effects to your system. USE AT YOUR OWN RISK.
You will need to manually create a registry entry for Call of Duty before you can install the patch. For this to work you must have installed to the default directory (c:\program files\call of duty).
1) Click Start, then Run.
2) At the prompt type "REGEDIT".
3) Click the "+" next to HKEY_LOCAL_MACHINE.
4) Click the "+" next to SOFTWARE.
5) If you see an Activision folder go to step 8.
6) Right-click on the Software folder and select New, then Key.
7) Name the new folder Activision.
8) Right-click on the Activision folder and select New, then Key.
9) Name the new folder Call of Duty.
10 Select the Call of Duty folder.
11) In the right window pane right-click and select New, then String Value.
12) Name the value "InstallPath" without the quotes.
13) Open the InstallPath string value by double-clicking on it.
14) In the Value data field type "c:\PROGRA~1\CALLOF~1" (without the quotes) then click OK.
15) In the right window pane right-click and select New, then String Value.
16) Name the value "Version" without the quotes.
17) Open the Version string value by double-clicking on it.
18) In the Value data field type "1.1" (without the quotes) if you have the original release of the game. If you have the Game of the Year edition type "1.3.1" (without the quotes)
If completed properly you will have a key named "HKEY_LOCAL_MACHINE\SOFTWARE\Activision\Call of Duty". This key will have a string value named InstallPath with a data value of c:\PROGRA~1\CALLOF~1 and a string value named Version with a value of 1.1/1.3.1.
Before the patch will install you must make sure you have entered a cd key for the game. Launch the multiplayer portion of the game. Click on multiplayer options. Click on the "Enter CD Key" button to enter your cd key.
You can now install the patch normally.
Also if you are depending on getting 1.6 i forgot where i got it!I think i got it off FilePlanet Forums or something i will get back to you but for now try 1.5!