Kick 3721 out of your system.

1. FILE Section

Delete the 3721 Installation File storage location, which is on disk C by default

C: \ windows \ Downloaded Program Files \
C: \ windows)
C: \ windows \ system32 \ drivers \
C: \ Program Files \ 3721 \

2. Registry

Delete 3721 junk in the Registry

There is a csnmin registration item under HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ Run ------ "rundll32.exe c: \ windows \ downlo ~ 1 \ cnsmin. dll, rundll32 ".
HKEY_LOCAL_MACHINE \ SYSTEM \ controlset001 \ Enum \ Root \ legacy_cnsminkp
HKEY_LOCAL_MACHINE \ SYSTEM \ controlset001 \ Services \ cnsminkp
HKEY_LOCAL_MACHINE \ SYSTEM \ controlset003 \ Enum \ Root \ legacy_cnsminkp
HKEY_LOCAL_MACHINE \ SYSTEM \ controlset003 \ Services \ cnsminkp
HKEY_USERS \ S-1-5-21-1708537768-1303643608-725345543-500 \ Software \ Microsoft \ Internet Explorer \ menuext \ quick search (yisou.com)

Hope that through the above efforts, you have been away from the troubles brought by 3721