Paau: "By the way, have any of your brokers contacted you yet to cancel your Crystallex shares? (Don't panic, it's fine.)"

By the way, Brokers CANNOT CANCEL SHARES. Only a court-sanctioned plan of arrangement or liquidation will result in the cancellation of shares. A  broker MAY cancel brokerage accounts, provided they meet the FINRA / CSC rules and regulations; one of which is that the holdings in the account can be either transferred or traded.

Delisted shares cannot be traded or transferred (unless there is another broker willing and able to accept the transfer). The issue here is that tax and legal issues make the sale and transfer of delisted stock complex and problematic. Hence, rarely, if ever, delisted shares are transferred between brokers.

If you are asked to take your delisted shares elsewhere, you will need to a) rely on the stock issuer or b) the stock exchange where the share was issued [if a) does not work], or c) the government agency that regulates the stock exchange involved [if a) and b) do not work].