You are using Apache Http Web Server. The dispatcher is not using the URL already processed by mod rewrite. You have made sure that the line DispatcherUseProcessedURL is set to 1 in the Dispatcher configuration.
In httpd.conf change
RewriteRule ^(.+)\.html(.*)$ $1.reg.%1.html$2
RewriteRule ^(.+)\.html(.*)$ $1.reg.%1.html$2 [PT]