first you need to use IE (mcp site don't working properly with chrome or mozila).
i think the temp password you get it's expire or the server was down for Maintenance.
My recommendation for you:
Open MCP Site with Internet Explorer.
Type your MC ID and your Temp Password.
if you can't login click on "Can't
access your account?" and select "I forgot my password".
</label>The system will send you an email to reset your password, do not forget to do so soon.