I get a Windows 10 error when executing SARMCM3.DLL in Keil V4.60. On the first debug session all works well, but when I quit debug, compile the project and resume debug UV4 is closed. Winodws log reports Exception Code 0xc0000005. When I run Keil V5.25 all works well.
Keil has a direct support structure, this is a user-to-user forum. See notes here http://www.keil.com/forum/
You can install different versions in different directories.
If the version you have is broken in Win10 your options are to install a version that fixed those issues, or use Virtual PC to run an older OS version. Best not to install a new OS on your primary development machine, Microsoft has a history of breaking and discarding things leaving a trail of wreckage decades long, and thousands of developers wide...