I run CFS2 on Windows 8.1. I often used to get issues with Norton quarantining .gau files, some .dlls and other assorted items that I am either downloading or unzipping related to CFS2.
But it is relatively easy to remedy. At the risk of telling you something you already know, here goes...
Open up Norton and go to "Settings". Click on "Antivirus" -> "Scans and Risks" -> "Exclusions/low risks" -> "Items to exclude from Auto Protect, SONAR and Download Intelligence detection" -> "Configure [+]" then add folders and items you wish to excluded from real time protection.
For instance, I excluded my CFS2 download folder as well as my entire CFS2 parent folder along with the folder where I keep all of my simming and scenery making utilities installed. You can also exclude the same folders from Scans too.
Momentarily turning off real time protection when downloading and unzipping files from trusted sources such as the files from CFS2 developers being downloaded from SOH and other trusted sites is also an option. Just remember to turn it back on!
Cheers,
MR
PS You are likely already aware of this too, but I mention it anyway: If you think Norton has quarantined a required file from your DOS-MDLC set-up you can always check using "View Recent History". If some needed file has been quarantined by Norton it it can be restored and excluded from any future notice by Norton.