Hey, I have pretty much the same problem. I get this error "iw3sp.exe has encountered a problem and needs to close. We are sorry for the inconvenience." I realise this is a generic crash, but it happens with both SP and MP versions of the game, and also once i've reinstalled. Seeing as its a similar error i'll follow your questions from the post above.
1) Is it a legit copy of the game? Meaning, did you actually buy it or just download it for free? Legit ofc.
2) Did you buy the game at a store or from Steam? Purchased from Steam
3) I know you said your computer meets/exceeds the spec requirement, but what kind of GPU (nVidia, ATi) and CPU (Intel, AMD) do you have? Also, are you running recent drivers for them? Exceeds minimum specification, fully up to date drivers. Nvidia gpu and AMD cpu.
4) Have you tried running the game in safe mode? Yes, same error
5) "iw3sp.exe" Error is a generic error when the game crashes, are you able to see the console to view what the specific error is? I could, how would i view the console?
Also i'll say that the first time I started the game it loaded fine through the intro movies and into the options screen. I changed the resolution from 800x600 up to 1280x1024 and also bumped up the refresh rate from 60Hz to 75 to match my desktop settings. Since then I just get continuous crashes. Safe mode doesn't seem to fix it, I wonder if there is a way I can reset the settings externally? Bear in mind i've already uninstalled and redownloaded the game.
Would really appreciate some help on this, otherwise its £30 down the drain