How can I remove what remains of the Yahoo program?

Have Windows ME: Yahoo was uninstalled in order to be replaced by Netscape. Remnants of the Yahoo program remain. Trouble signing on, with notice that another program is dialling up. Trouble running Scandisk, with notice that another program is "writing to the drive," when running Spybot, notice that "another program is dialling the connection." Believe other sundry mischief may also be traceable to same cause. What do I do? Does Yahoo or anyone else sell a software specific to this problem? Am unable to reinstall Yahoo, as it's deleted permanently (what of it was actually deleted. I'm an extreme novice, first computer.Also, sometimes when dialling in I receive a notice that the port is already occupied.