I have been using fiddler core for a while now and the problem I've been having (which only recently started happening) is that when I try to capture/decrypt SSL with 'CertMaker.TrustRootCert();' it prompts me each time to install the certificate. I have used this code before and this has never happened.
This is my startup code if you need it >
oSecureEndpoint = FiddlerApplication.CreateProxyEndpoint(iSecureEndpointPort, true, sSecureEndpointHostname);
FiddlerApplication.BeforeRequest += encodeOnReq;