Where to change error message Ubu 10.04, ISPConfig, Apache2

Hi,

I have ISPConfig running here using SSL, but using a different port to default. Everything is working, however I NEED to change the error message displayed when someone types http://mydomain.tld:ISPConfig_Port (instead of HTTPS:). Not looking for a redirect, legitimate users should be able to figure this out.

So my only problem is the error message contence shown below:

(I don't want my hostname (Not Subdomain) being displayed. And the suggested hint doesn't work either)

400 Bad Request (shows in browser's title bar)

Bad Request

Your browser sent a request that this server could not understand.
Reason: You're speaking plain HTTP to an SSL-enabled server port.
Instead use the HTTPS scheme to access this URL, please.

    Hint: https://hostname.mydomain.tld:ISPConfig_Port/

For the life of me, I cannot find where this error text comes from. (I'm not that good with linux or the grep command, so I'm searching the net instead.) I've found a few places where error message texts are kept;

1) /var/www/vdomain/web/error, and

2) /usr/share/apache2/error

Any help please.