Maybe this could help:
In 'run' - msconfig - program tab:
uncheck the Firefox
uncheck the thunderbird
uncheck all but just the
"run dll" & all taskbar
and virus protection
(you could try unchecking your AV pgm too)
from loading at startup.......
.......click 'apply' and 'OK'
.........reboot
.......go back & doublecheck that anything unchecked
doesn't come back again on its own- see if it does.
This only stops from loading and running at startup.
All pgms can still be launched from the start menu