I have had to address many problems with older computers trying to update to Windows 10; some of those problems were the fact that the computers were just too old, not enough processor power, too many trojans in their soft ware and some had too old of BIOS. Before you attempt to do the update to Windows 10 (any version) make sure that you have the latest BIOS. Doing so, could have saved many people a lot of money and time. Even some new Windows 10 computers could use a BIOS update. Just thought that you might like to know.
Mary: It might depend on what computer you have, but here is how I update BIOS in a DELL computer (laptop/desktop/all-in-one): I first check to see what version of BIOS I have on the computer. Than I go to DELL/Support and select my computer from their listing. Than I select update drivers manually. I select the BIOS and tell it to save the executable file in my down load folder. I go to the down load folder and run the BIOS(exe) file. If everything goes well, the computer will run for a short time and than re-boot and finish installing. I always check to make sure that the new up-date is working (I check the BIOS version). Up-dating to the newest BIOS solves a lot of software problems.