Stocks of Bankrupt Companies and Capitol Loss

Hi,
I've got some stock in LEHMQ, WAMUQ, and VNBCQ. Is there a possible outcome where I won't be able to claim a capital loss on it?

I sold $3k of it last year, and plan to sell another $3k this year, but was waiting till December. Do I need to sell before something happens, like they just plain disappear, or can I still claim if they completely delist?
Thanks.