Finally, no more red circle with slash on tray icon after reboot. After performing numerous registry scans and manually searching the registry for anything related to Symantec, Systemworks, Ghost, etc. (except for those entries necessary to Windows firewall), the problem is fixed.
As I mentioned previously, I used Symantec's removal procedures, several times in fact, but there were still dozens of references left over.
Avast now starts when my computer starts. Yay!