Strange serial behavior - possibly bad UART or serial->usb converter?

Development Tools IDE 1.x
1

Platform: Uno R3
OS: Windows
Terminal: serial monitor and br@y terminal.

Update: While the original problem is still valid, I decided to do the loopback test to see what the results of that would be. It seems like there is a definite issue, that is much worse at lower baudrates, but I'll leave the original post in anyways.

The issue isn't noticed when typing slowly, but when using a terminal macro to send a string the issues are noticable. This is why I probably didn't notice it as much using the wifly passthrough because I was typing out commands, but outputting the data coming back from the wifly was often garbled.

Ideas?

9600: (clicking the macro button slowly).

This Is A Test
st
This Is A TeThis Is A Test
This Is A Test
This Is A Test
Is A Test
This 
This ThITest
This ThIThis
s A Test
s A This
s A Is A Test
s A This

115200:

This Is A Test
This Is A Test
This Is A Test
Is A Test
ThiA This Is A Test
This Is A Test
This Is A Test
This Is A Test
This Is A Test
This Is A Test
This Is A Test
This Is A Test
This Is A Test
This Is A Test
s A Test
Thi TeTest
Thi TeThis s A This Is A Test
This Is A Test
This Is A Test
This Is A Test
This Is A Test

Original Post:

I originally started out this project with a wifly shield, communicating with the wifly over softwareserial. I was getting some strange output when using the arduino as a passthrough terminal to the wifly (for testing commands etc without having to breadboard it). It worked fine most of the time, especially for sending, but a lot of the time the data coming back would get garbled and sometimes repeated. Some of that I think was not flushing the buffer correctly before looping, but I thought the issues were probably with the softwareserial communication.

I eventually stripped everything back off and realized that simple serial output from the uno to the terminal had problems. I don't have a lot of experience with arduino (I've done straight avr programming with avrlibc in the past), so I want to see if perhaps I'm missing something simple. There is no extra configuration, no wires at all, just the standalone board, no jumpers. I have tried different baudrates with no noticeable difference.

I have a ttl->rs232 converter in the mail, at which case I was planning on using that with a usb->serial converter I have to see if perhaps its something else, but that will take several days.

Any ideas? Am I going crazy?

Thanks.

Using Serial.write:

Code:

void setup()  
{
  Serial.begin(9600);
}

void loop() // run over and over
{
  if(Serial)
  {
    Serial.write("HelloWrite\r"); 
    Serial.flush();
  }
  
  delay(500);
}

Output:

HelloWrite
HelloWrite
Write
Heitee
HeiteHelloWritHelloWrite
HelloWrite
rite
Hete
WHelloWrite

HelloWriteloWrite
HelloWriteHeWite
HelloWriteHeWHte
oWrite
oWrHee
oWrHelloWrite
te
He
loWrioWrite
loWriHWrite
loWriHWriHe
loWriHelloWrite
Write
HeiteWrite
HeiteHeitee
HeiteHeiteHelloWritHelloWrite

Using Serial.println:

Code:

void setup()  
{
  Serial.begin(9600);
}

void loop() // run over and over
{
  if(Serial)
  {
    Serial.println("Hello1234"); 
    Serial.flush();
  }
  
  delay(500);
}

Output:

Hello1234
Hello1234
Hello1234
Hello1234
Hello1234
Hello1234
Hello1234
Hello1234
lo1234
He134
He1Hello12Hello1234
Hello1234
o1234
Hel3Hello1234
o1234
H123Hello1234
1234
He34
1234
Hel4
Hello1234
234
H34
1Hello1234
234
He4
1Hello1234