Infinite uploading

Hello forum,

Using my arduino due, I just noticed that when I try to upload my sketch, I either get an infinite upload (never completes) or I get an error code. Either way, reinstalling drivers etc. etc. doesn't work and I'm starting to fear this is a problem with my board. I will include both error codes, as the infinite upload also displays some error codes.

this is the infinite uploading code:

processing.app.debug.RunnerException
    at cc.arduino.packages.uploaders.SerialUploader.uploadUsingPreferences(SerialUploader.java:162)
    at cc.arduino.UploaderUtils.upload(UploaderUtils.java:78)
    at processing.app.Sketch.upload(Sketch.java:1187)
    at processing.app.Sketch.exportApplet(Sketch.java:1160)
    at processing.app.Sketch.exportApplet(Sketch.java:1132)
    at processing.app.Editor$DefaultExportHandler.run(Editor.java:2409)
    at java.lang.Thread.run(Thread.java:745)
Caused by: processing.app.SerialException: Fout bij het aanspreken van de seriƫle poort "COM5"
    at processing.app.Serial.touchForCDCReset(Serial.java:87)
    at cc.arduino.packages.uploaders.SerialUploader.uploadUsingPreferences(SerialUploader.java:146)
    ... 6 more
Caused by: jssc.SerialPortException: Port name - COM5; Method name - openPort(); Exception type - Port not found.
    at jssc.SerialPort.openPort(SerialPort.java:167)
    at processing.app.Serial.touchForCDCReset(Serial.java:81)
    ... 7 more

this is the one I get for larger codes:

C:\Users\gillian\AppData\Local\Temp\build04ab5278adf08dec5c4a77179f8d33ba.tmp/core\core.a(main.cpp.o): In function `main':

C:\Users\gillian\AppData\Local\Arduino15\packages\arduino\hardware\sam\1.6.9\cores\arduino/main.cpp:61: undefined reference to `loop'

collect2.exe: error: ld returned 1 exit status

exit status 1
Fout bij het compileren van board Arduino Due (Programming Port)

Hope someone can help me!

Regards, Gillian