I get no such error using Chrome. Cert looks good.
Issuer:
CN = PositiveSSL CA
O = Comodo CA Limited
L = Salford
S = Greater Manchester
C = GB
Subject:
CN = btc-e.com
OU = PositiveSSL
OU = Domain Control Validated
Alternate Name:
DNS Name=btc-e.com
DNS Name=www.btc-e.com
Either it is a bug in Firefox 10 or you got some url redirection going on.