Difference in delivery of special char via HTML page over SSL. Encoding rules?

When dishing out HTML having a special character like half fraction

<li>½ tsp salt</li&开发者_Python百科gt;  [HTTP]

it shows fine over HTTP. We are not explicitly encoding it as we should be: &

However, the same HTML, when delivered over an SSL connection reveals the character as garbled with question marks in the source (using same browser) like so:

<li>?? tsp salt</li>  [HTTPS]

Despite the fact that we should be encoding these entities properly, this is not what the question is about ( we know how to solve that problem ).

Can anybody explain how the SSL encoding works such that there's a difference in delivery of the same special character over HTTP vs HTTPS, in the same browser?

More Info:

• We're using IIS7 and a certificate from GeoTrust.
• Any browser can be used to show the difference in SSL mode vs standard HTTP

SSL won't make any difference here. The problem may be coincident with the use of SSL, but it isn't SSL that is causing the problem.