Stereo keeps re-setting

Just bought a Mk 4 golf the other day (98). Removed the Gamma stereo that came with the car and fitted my Sony CD player in its place. All was going well until the next time I started the car up and the stereo had reset to the factory settings. i.e lost the time, the radio presets and bass / treble settings etc. This happens every time you remove the key from the ignition. This was not a problem with my last car. Any ideas of how to sort this out would be welcomed.

bad installation! there is a wire thats for memory that will give the sterio power all the time for the memory you must have not used that! try to get a harnes for your car and install the wires to the harnes and it should do fine!

Thanks, you were right, it was bad installation...rewired the system and it seems to be working fine now....All happy this end....Thanks again....