It might be that the Memory modules are bad or possibly not seated properly in the DIMM slots. Also, some Memory sticks may not be compatible with the Motif ES. A Brand name memory stick is usually of better quality than its generic counterpart and would most likely have a better chance of working with the Motif ES.

PS: The above statements were said because you said the contents of the Sound Library might somehow have gotten corrupted when you powered down. If something is getting corrupted then the Memory may be to blame.

OTOH, if you say you are simply losing the Voices you loaded when you power back up the Motif ES then the problem most likely is that you did not 'save' the Voices in the Sound Library you loaded into the Motif ES before powering down. It's been quite a while since I've had my Motif ES7 but the Manual should explain to you how to save the Voices you want. If my memory serves me correctly you have to transfer the Voices into the User Program Bank[s] first then initiate the Save function before exiting and powering down. But read the Manual as it will explain the process thoroughly. The Table of Contents in the Manual should point you in the right direction on "Saving Data that is Loaded into the Motif ES", etc..

Hope this helps,

Mike