some applications not working in Windows 10 Technical Preview

I have recently installed this latest Windows 10 Technical Preview operating system in my pc. Windows got installed without any issues but when I am trying to install certain applications that used to work in Windows 8.1 then it is giving me some error message. For instance, installing K-Lite Codec Pack keeps giving me error message saying that "The file C:\Windows\SysWOW64\regsvr32.exe has an incorrect version. Please replace the file with a genuine copy. Setup will now abort". Then there are also various antivirus which is not compatible, such as KIS, F-Secure, Symantec Endpoint, Norton Security, Norton Secure ID and also Microsoft Sculpt Comfort Mouse. They all cannot be even installed in Compatability mode. Any ideas

This operating system is a Windows 10 Technical Preview and in a testing phase, so what else do you expect it to support. Either ways, it looks to me that in this Windows 10 the .Net 3.5 Windows feature is still not installed by default, like in Server 2012 R2 it had the same behaviour. So, what you can do is try to install the Windows Feature and check for updates through the Windows Update and see if your software is able to install in your pc.

Can you try to run the below command in an elevated Command Prompt and check if that works:
Dism /online /Enable-Feature /FeatureName:DirectPlay /FeatureName:netfx3

You might also need to ensure that your old Operating System was updated fully before you have installed the Windows 10 Technical Preview. Since this OS just came out this month so I think that most of the people wo have installed it on their pc will not be able to install any antivirus software for another few month. It is going to take some time for them to work on something which just came out and once it is finished everything will be supported fine then.

Well, if you are looking to install any third party antivirus application then I have found that Bitdefender antivirus can be installed fine on Windows 10 Technical Preview. There is another antivirus called Qihoo's 360 TS but I will not suggest to install this antivirus since it is not a reliable software, I found it from a data security standpoint. You can also try to install Avira which is working in some of the Windows 10 user's computer.

Try a quick sweep with quickheal! It should work :)