Well, regarding everyone who is unable to get MHS working, I found a UCE that works, and hopefully it will work for you.
Have fun & enjoy!
Credits to the creator of the UCE.
Note: To anyone who assumes this is a virus, scan all you want.
By the way, if still get issues.
You'll probably need ACPI MODE.
So, do the following:
Right click 'My Computer' and choose Properties
Choose the 'Hardware' tab and click 'Device Manager'
After you have completed that, look at 'Computer' and Click the [+] sign
Right click 'ACPI Multiprocessor PC' and click Update Driver...
Click 'Yes, and this time only'.
Choose "Install from a list or specific location (Advanced)" then click the 'Next' button
Choose "Don't search. I will choose the driver to install" then click the 'Next' button
Highlight "Advanced Configuration and Power Interface" then click the 'Next' button
Wait while the wizard installs the software...
Do you want to restart your computer now? Click Yes!
Note: The hardware you installed will not work until you restart your computer. You may have to restart twice
ALSO: If you're still getting problems, click the 'Bypass' button before you load Combat Arms! Or try clicking the 'Bypass' button when in-game too!