Firefox and Error 623 (Archive)
Sometimes the Dial-Up Internet Connection under Windows has some strange bugs.
Internet Explorer works, but you lovely Firefox will tell you, Error 623, no phonebook entry:
"Cannot load dialog
Error 623: The system cannot find the phone book entry for this connection"
The problem is quite annoying but maybe my tip can solve the problem:
Check if you have an old ras connection name in:
HKEY_LOCAL_MASCHINE\SOFTWARE\Microsoft\RAS Autodial\Default
There is a "DefaultInternet" key, simple change the old name to an existent name (dialup connection).
Now Firefox should start without showing a windows bug :-)
If you can't find the error there or it doesn't work you may find the same problem here as well:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\RAS Autodial\Default
Sometimes it's quite hard even for Microsoft Programmers to remember all locations where something should be set :-)