Most likely you'll just need to point Sampletank to the location of its included sample files. To do this, in Sampletank:

1. Click the ROOT button
2. A file box will pop up, navagate to My Computer - C drive - Program Files - IK Multimedia - IK Digidesign Bundle - Sampletank Instruments
3. Click OK

Your instruments should now show up and you should not have to point Sampletank to this location again.