To add to what Larry K. describes, about 2 years ago <a time long ago and a place far away> similar problems were experienced with Hi-Q tags in the SampleTank VSTi, and a step by step solution (Larry K's, but for dummies like me) was posted.

You can help verify the lost instruments message refers to Hi-Q stuff by right clicking on the radio button of a midi track at the top of the screen; choose the 'Select Hi-Q midi synth patch' and you will get the error message in every case if the folders are a lost tribe.

At that point the Larry K's advice and the following will probably fix you up: http://www.pgmusic.com/forums/ubbthreads.php?ubb=showthreaded&Number=192278. Or just type in <192278> in the forum search box. The step by step fix process is visual and easy to follow.

I had the same problem you describe after installing BIAB 2015 over 2014 and the fix worked, but I needed the above reference to help me sort it out.

I have the full version of SampleTank 2.5 and have ordered the SampleTank 3 (64 bit only) (used with JBridge in BIAB 2015) and expect to have a similar sort it out session when I install it.

John E.