I have a webserver (IIS) with an SSL cert for *.mydomain.com
This works perfectly for https://anysubdomain.mydomain.com/ but going to https://mydomain.com/ causes a certificate mismatch error in IE (has not been tested in all other browsers).
Is there any way to work around this, or is it simply a problem with the way IE treats the wildcard in the certificate we have to live with?
The only way to remove the error message when accessing the site at https://mydomain.com is to put the base domain (mydomain.com) in as a Subject Alternative Name in the wildcard. Several certificate providers will add this for free (including DigiCert and Comodo) but you will need to reissue your certificate.