Similar thing happened to me just sucking up a rubber carpet underpad that turned to "dust"... The vacuum canister was building up enough of a charge to throw an occasional arc 1 1/2"- 2" between the vacuum's metal handle and the freezer door of which it was parked beside.. I have NEVER seen anything as bizarre as that before..
A small "cheater" between the metal canister of the vac and a nearby device box took care of things until I was finished vacuuming.

A.D

[This message has been edited by Rewired (edited 12-14-2006).]