Abnormal arduino behavior on new computer .

i have 3 arduinos , 2 arduino uno and 1 Arduino mega . with my old computer i used to be able to program them well without problems and everything used to go just fine . i recently acquired a new computer . i installed the IDE and everything went well . but when i upload code on the Arduino , it runs abnormally . the code uploads just fine but then the output is abnormal .

here is an example with an Arduino mega :

this is the test code :
test_code.png

this is get during upload which is normal :

then this is the output : it prints "he" then prints "h" forever until i shut it down , which is abnormal

test_code.png

Perhaps try a small delay() in between the .begin and .println commands

hello Bos thank you for your response , i added a delay of 100ms , and then there was no output at all .
even standard examples don't work . i uploaded the standard arduino Blink from the Arduino and even that didn't work , the led wasn't blinking .
something off is going on .

Is there a way you can monitor the voltage on the reset line of your boards? Perhaps the device is perpetually resetting itself which causes the continuous printing.