First get this file: http://www.tweak3d.net/files/Pak2.pak
Now get this file: http://pages.eidosnet.co.uk/~noghri/dl/pakxp.zip
Open the pakxp.zip file and extract the PakExpl.exe file somewhere.
Double-click the PakExpl.exe that you extracted and click "OK" on the screen that comes up, next go to the "File" menu and select "Open Pak"
then locate the Pak2.pak file you downloaded before and open it.
Double-click on the gfx folder that appears, and then right-click on the "palette.lmp" file and select "Extract".
Now goto Find/Search on your "Start" menu and search for "palette.lmp", right-click it and select "Cut" then goto the ...\Half-Life\cstrike\gfx folder and "Paste" the file there.
This should solve that particular error.