"...is there anything which can stop them doing so..."No.It...

"...is there anything which can stop them doing so..."

No.

It would only take one of ANY of the creditors owed to call in the debt, and it's all over for CNP....unless of course their debt is paid out by the other remaining creditors, and that would be more than extremely unlikely.

Naturally, I would hope that none of this eventuates, as it would wipe out existing shareholders, and have a detrimental effect to the market as a whole, but in light of events of late, IMO I cannot envisage a different outcome.