I am having issues with Mindows media player, 10 or 11 I'm not entirely sure which as I've downloaded both. Everytime I open it, a popup window wioll say wmplayer.exe- Entry point not found the procedure entry point _itow_s could not be located in the dynamic link library msvcrt.dll. After clicking ok, another pop-up comes up saying windows media player has not been installed properly and must be reinstalled. How do I fix this issue? I've uninstalled and reinstalled it about 4 times today and 5 times yesterday, yet the issue still persists.

I suggest you remove all instances of WMP and reboot. Download CCleaner and run the registry module. Then reinstall WMP. WMP 11 requires at least SP2 be installed. Look at the link below. http://support.microsoft.com/kb/925850

This may seem idiotic, but does installing SP3 affect WMP? I ask because instant updates is telling me to update my SP2 to 3

There may be some updates to WMP included in the update. You may already have most, or all of the updates if you use Windows auto update. Re-installing WMP should give you the latest version. If you get it from the Windows site.