Sketch will not run

Hi: First time user. I can't even get the "blinking LED" sketch to ru. Windows Vista, Arduino Uno. The sketch compiles and loads no problem but does not run? Green LED is on, Yellow LED on solid, my LED is off? What is happening? Thanks

please post your sketch (use the # button for code tags) and your schematic, then we can have a look!

“Green LED is on, Yellow LED on solid”
That would indicate the USB port is seeing continuous action - what do you have going on?

I do not know? I got this error "avrdude: stk500_getsync(): not in sync: resp=0x30". After a lot of reading and following trouble shooting guidelines without any success I bought a new Arduiono board. The new one worked fine, I loaded programs and ran them for two days. Then this morning got the same error. The program I last loaded is stll there and runs fine, just can't talk to the board to load others. When I load programs withy the USB cable the board uses the computer power source, when I run it after I power the board with a 12v battery on the "Vin" pin. Is that a problem that blows the board? Thanks, Bela

I got this error "avrdude: stk500_getsync(): not in sync: resp=0x30". After a lot of reading and following trouble shooting guidelines without any success I bought a new Arduiono board. The new one worked fine, I loaded programs and ran them for two days. Then this morning got the same error. The program I last loaded is stll there and runs fine, just can't talk to the board to load others. When I load programs with the USB cable the board uses the computer power source, when I run it after I power the board with a 12v battery on the "Vin" pin. Is that a problem that blows the board? Thanks, Bela

Does the regulator or any other part get really hot or anything?

I know when I power a Duemilano from 12V to control 4 MAX7219 and 8x8 matrixes, the regulator overheats and the board resets a lot after about a minute.
If I power from 9V, or from USB, the board runs fine. The combination of high voltage and lots of current, but still <500mA, is too much.

I can build a 5 V regulator supply on my breadboard and power it with that. Do you think the 12 V is what is causing the prblem with the Arduino. Does it not protect itself from overvoltage? Thanks.

Is that a problem that blows the board

No powering the board like that is fine. More detailes about what you are running and how it is wired up would help try and find out why it happens. Also what sort of arduino?

Thanks guys, I bought another board and now everything works fine. Still have a little trouble with specifying the ports. If I do not load the drivers every time I start the computer it will not talk to the Arduino but I will figure that out. Thanks again.