Heya,

So the case is now resovled although im not sure if this is something you can do on mirc.
Perhaps making a update to the help file will be the best option just incase.

She copied her certificate information incorrectly thus the RSA key didnt match the certificate and this gave the error, as mentioned, can you make mirc give a better response IF theres a mismatch? If not i think perhaps a post somewhere about it should help any additional people in the future.

Many thanks for your help Khaled!!