This is usually a sign of a corrupted ISO file. Delete the file and re-download it from a different source. Ensure the file size matches the description (don't trust a 5MB file claiming to be FIFA 15!).
: Expect the same blurry player models and pixelated crowds seen in previous years, as it lacks the "Ignite" engine used on newer systems. The "ISO" Scene fifa 15 iso psp
: You will need the FIFA 15 ISO or CSO file. Emulators like PPSSPP on Google Play recommend creating these files from your own legal physical UMD collection. This is usually a sign of a corrupted ISO file