But at 4 months ago I hope you called it in and have a transaction number from that call. You might be able to pull it in under warranty if you have that call and number.
If not, and it's just over a year head to samsung.com and register your product. SOMETIMES you get 3 more months of warranty so you can call it in and get it fixed.
I have a Samsung Syncmaster 2343 23" monitor for about a year. About 4 months ago it would just randomly go off. Checked cables, power cord, new cables, etc and tried on a different computer as well. I read it might the transformer/power supply? But it stopped doing that and worked fine until yesterday and now it does the same thing.