I can't speak for the retailers, but the service plan you purchased through them came from a third-party warranty company. So even if the company does out of business (I really can't speak to that effect, so we'll leave it at that), you are still covered by the warranty.
The good news is that you're covered under Samsung's warranty for the first year, so if it requires a repair, you can get that regardless.
I would suggest downloading the latest firmware for your unit. What is your exact model number? I'll be happy to point you in the direction of that if you'd like, as that usually solves the problem.
Have a Series 5 37" (purchased approximately 6 weeks ago) LCD Samsung that, more and more frequently, the picture goes black while the sound continues. If I turn the TV off then back on the picture reappears. This is now happening as frequently as every 5 minutes. I have keep the TV unplugged for as long as two days in hopes that it would "reboot" and fuction properly but the problem is getting worse. Bought it at Circuit City and have the extended warrenty but I am not sure that store is still in business.
What should I do next?