Hi. Whenever I try to install Ubuntu Mate 15.10 from USB it does not recognize Windows 10 on my system; In fact the installer says there isn’t any other OS on my computer. How can I make the install alongside Windows option appear?
I have never experienced that before and I have installed quite a number of dual boot systems. Not that I am doubting your word. I know it will be a pain, but would it be possible to try and do the installation and, as you do it, take photos with your phone o each of the installation screens as you come to them? Then, when it gets to the point where you can go no further, stop the installation and re-log back into UM and then upload the photos to here. That way, I should have a better idea of what is going wrong for you and so be able to give you appropriate advice.
It sounds like Windows 10 is installed in UEFI mode, but Ubuntu MATE is booting in BIOS mode.
This Wiki article will help if this is the case:
https://help.ubuntu.com/community/UEFI
You could also check if the disk is just seeing a “protective layer”, which is used to prevent the BIOS mode from overwriting the disk (thinking the disk is empty) as the two modes are not interchangeable.
To check that, open a terminal from the live session by pressing CTRL+ALT+T and type sudo gparted.
Ah right, yeah…I experience some kind of funny business at boot-up with a USB. Rather than set it to automatically boot to a USB, if present, I have to manually boot it by pressing f2. Then choose from one of two options. I can’t remember the name of them, but is is always the top one, cos if I choose the other one, it wont boot. The reason I boot it with f2 is cos it defaults to the inoperative boot one otherwise.
Hello! I’m also having trouble dual booting with Windows 10, so I’m writing my question here, instead of opening a new topic.
My problem is, namely, that installing Ubuntu Mate after Windows 10 seems to mess up the installation of windows, even though I choose to install it alongside it. I get the option to choose the operating system, but when I try to access Windows, I get the notification that it is “broken” (what ever that might mean). When installing Mate I get the notification that additional partitions will be made and formatted, so I’m guessing that something goes wrong at that point? Any suggestions or ideas? Thanks 
I’m not too sure what you mean. Have you got a screenshot? Is it a blue screen saying something like “Your system needs repairs” with an error code?
If you can repair the bootloader via Windows, that may fix it, but could potentially wipe out GRUB, which is the bootloader used for booting a Linux OS. (That can be easily re-installed again from a live session)
The dialog box informing about creating additional partitions is normal. There’s a partition for Ubuntu, then another for swap, which is the equivalent of a pagefile in Windows.
I don’t have a screenshot, as I re-installed Windows, since I have to use it for work.
But yes, I do get the notification that my system needs repairs, only no error code. Then the system tries to fix the error - unsuccessfully - and I can’t access Windows in any way. If I choose the option called something like “Exit and proceed to Windows”, the computer simply reboots, prompting the same blue screen again.
Does it matter which program I use to create a bootable USB? I used Rufus last time.
Some tools under Windows pose a problem, but according to another user, Rufus seems to be fine for writing a USB image.
So, why Windows “had problems”… Well, it could depend on how you resized the disk. It’s safer to do it within Windows using the Disk Management tool, and then let the Ubuntu installation wizard install to the new unallocated space. The new Welcome utility in 16.04 explains this. 