Well thats fixed it!

I uncompressed the downloaded image file and wrote it to the SD card and it works!

Thanks for you help

drgeoff wrote: There is no downloadable image for Ubuntu Mate. The download is a compressed version. Did you extract the img file before writing with Win32DiskImager?

I didn't realise the image file was compressed! Will have to uncompress it and try again!

Had the Pi 3 for around 2 weeks now, no problems so far :D Thought I would try Ubuntu MATE, and I have downloaded the image and written it to a new SD card. The SD card was formatted using SD Formatter, and the image was written using Win32DiskImager both running on a Windows 10 PC. The SHA checksum...