wrote:

Let's clarify what "damaged PK3" files can mean... If its a install off the CD, then the other most likely problem is a different pk3 file in your baseq3 dir which is overwriting the base textures with its own. If you dont have that many custom maps installed, just try moving all the pk3 files to another directory (everything except pak0..pak8) and then put them back one by one until you see which one is causing your problem.

my suggestion is to first delete all tmp files in your baseq3 and excessiveplus folders

most of the time suvh problems are caused by autodownloading crap from servers. you dont need any of that stuff, and it does you no good cause it is incomplete.

if it doesnt work, try the above suggestion by starless

That black and white checkerboard means you are missing textures. But the map looks like q3ctf4 so you should have those. Try checking your console for 'trying textures..'. Also, are you loading the mod from the Q3 menu? Use a .bat file or shortcut instead.
Kinda OT but if you prefer the mouse in 1.16 then change in_mouse to "-1" and lower sensitivity to what you're used to.
More OT; some maps don't have textures from a pk3 called mapmedia.pk3. It comes in the Q3 map editor but not Q3 so you might want to google this one.