Try pressing the home button at the point where it says Ubisoft and then wait a little then press home button again this worked for SEGA Superstars Tennis when it freezes at SEGA logo.
Simple possible fix for SEGA Superstars Tennis (PAL) all you need to do is press the home button right at the point where it says SEGA and then simply press it again and the game should run normally. Hope it helped!
I have (PAL) Wii