The .pem cert bundle must be built in a specific order to be properly read by haproxy.  After obtaining a new cert package from Comodo, the file names will have STAR_ prefixes.  First remove those.

Next, combine the following files into a new one called main_ringfree_biz.pem:

# cd /etc/ringfree/certs/
# cat ringfree_biz.key > main_ringfree_biz.pem
# cat ringfree_biz.crt >> main_ringfree_biz.pem
# cat ringfree_biz_bundle.pem >> main_ringfree_biz.pem

Afterwards, restart the haproxy service:

# service haproxy reload