I assume you are getting the download image fail message.
There are a few things you can try.
1- Always use Firefox when downloading images from the extreme site. Other browsers try to extract the file or rename it.
2- Always check the MD5 checksum to make sure the file was downloaded correctly.
3- If you are using a USB key. make sure the ERS can see the USB file system. "Show usb-file".
4- if you are using TFTP make sure any firewalls on your laptop aren't blocking its ability to share files.
