Accck! You should have kept NS4.75, since it is a completely separate program from the NS6/NS7 lines. Under NS4.7x, the Netscape executable file is named NETSCAPE.EXE, and thats what McAfee was looking for. I'm guessing that it uses Netscape to call home and check for upgrades and such (if Netscape is the default browser). The NS7 executable has the label of Netscp.exe. (I don't remember what NS6 calls its executable file.) The McAfee people should have been able to figure this out.
The other problem which involves McAfee files is beyond me since I stopped using McAfee past version 4.x. Norton AV is just a bit better in its behavior (so far). The McAfee people should be able to tell you how to get any browser to work with their system.
The advice below is speculative and, considering it comes from an eccentric professor, should only be regarded in a poor light.
You might want to strip out NS7 (and maybe McAfee), re-install Netscape 4.X, and then re-install NS7. Ramona has the world's best pages to describe how to do a Clean Install and Custom Install of Netscape6/7 at:
http://home.att.net/~cherokee67/ns67cleaninstall.html
http://home.att.net/~cherokee65/index5.html
You could try re-installing McAfee somewhere along the line here. You should be able to keep all your old NS7 bookmarks and E-mail since the NS7 profile is left behind after an uninstall. (Moving that stuff from NS7 to NS4 is beyond my knowledge at this point.)
It should also be easy to install NS4 after NS7. (It may not, however, solve your McAfee problem.) If there are any problems in doing this, I would have to let the more experienced hands on this forum help you, since I have never installed NS4 after NS6/7. The only problem that I could imagine is setting which browser would be the default (and whether McAfee cares).
Take the above info with a bit of salt and maybe wait for more reliable info from a better source.
UserAgent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0 (nscd2)