In reply to Phil West:
Yep, that's been a common thing with Salomon and Scarpa boots from that time, the bond in the compound degrades and you get a pile of black powder. Last I tried (10 years ago) nothing could be done, but maybe these days there's a solution as I'm sure a lot of people have found the same thing.
Damn shame as that was also a good era for quality leather uppers (I had some leather lined Scarpas that did this that could never hit the market now), so I hope you find something.