Here is a suggestion, tell them to state their intentions or go away. Once they state their intentions tell them they have to sign a Memorandum of Understanding about what you're going to talk about and if they walk away it will cost them $X million (pick a number that would be able to resolve your debts and pay off any investors with a slight return).
What ever you do, do NOT be lured into thinking they are thinking about maybe a big exit for you, your interests are not aligned yet and you need to realize that. If there is any IP possible make sure you have provisional patents filed before you talk to them about anything. Even if you don't think it is patentable, force them to either buy you or risk infringing you if they go into competition with you.
Seriously, you have nothing to gain from this distraction if they aren't serious, and if they are serious they will put it in writing for you.
What ever you do, do NOT be lured into thinking they are thinking about maybe a big exit for you, your interests are not aligned yet and you need to realize that. If there is any IP possible make sure you have provisional patents filed before you talk to them about anything. Even if you don't think it is patentable, force them to either buy you or risk infringing you if they go into competition with you.
Seriously, you have nothing to gain from this distraction if they aren't serious, and if they are serious they will put it in writing for you.