Same here, a few years ago, with my HP-71B 'pouches'. In my experience, there are two reasonable things you can do, in this order:
1) Wash the offending pouch thoroughly, till all the disintegrating dust is completely eliminated. You'll know it's enough when the pouch, once dry, expels no dust whatsoever under strong agitation and severe tapping with the hand over a blank sheet of paper.
Afterwards:
2) Place your calculator *inside* a Teflon plastic envelope, which can be either thermo-sealed if it's just a collector's item intended for long storage, or else left open if you use or take out the machine frequently. Then place the teflon-enveloped machine inside the pouch.
This will prevent any further 'contamination' should the pouch keep disintegrating but even better, it will absolutely protect your valuable calculator against any scratches and wear (such as logo wear on the Voyager series and the 71B).
I do exactly like this, with excellent results over the passing years. Frankly, putting an HP-15C, say, in and out of its original tight pouch on a frequent basis should be regarded as criminal behavior.
Best regards from V.
Edited: 15 Sept 2004, 9:17 a.m.