Unable to download sketch

Hi,

I have an arduino Mega 2560, and as soon as it gets power the tx LED lights up and will not go off. I try to upload a sketch and it stalls the program at "uploading" and doesn't download the program. Furthermore, as soon as I plug in my arduino the program freezes up, and I cannot click on any of the toolbar dropdown options at the top. I can only click 'verify' 'upload' 'save' etc. I can't open up serial monitor or any of the options. I have tried both versions 1.04 and 1.01. Any ideas what is going wrong?

Sounds like the current sketch is flooding he USB buffers.

Hold down the Reset button.
Unplug and re-plug the USB cable to clear the buffers.
Click on the upload button for the sketch you want to upload.
When you see the Receive light blink, release the Reset button.

is it an official board or a clone?