Have you tried uninstalling both Firefox and Netscape and reinstalling?
Have you installed Sun's JRE? If so, what version is it? If not, try installing that, making sure that it's the latest version.
Since Netscape is built from Mozilla code (I think), that Mozilla registry file error may apply to either of them.
Firefox has an extension that lets it appear as another browser. Tools->Extensions->Get New Extensions, then look for User Agent Switcher.
I don't know about the picture/image problem. Sorry. Perhaps after doing the above it will magically go away. No promises, though.
Alrighty - good suggestions! I did not install Sun Java (JRE?). I'll do that first. If that doesn't do it, I'll uninstall and reinstall both browsers.
Thank you very much!