This issues are only being experienced by Windows users because according to iH8Sn0w "blackra1n hooks to the dll that has different offsets of what it is actually looking for"
iH8Sn0w has since released a blackra1n fix for iTunes 9.1 which can be downloaded from here. Both 32Bit + 64Bit are supported.
Please note this is not an official update from Geohot. Its unclear if he plans to release one.