It should not be necessary to adjust firewall settings.
If you have 'Speedbit' installed, lose it, (known conflicts with Yahoo)
Sounds like you may have tried to download without clearing out your
browser or failed to check the Messenger file was empty before
uploading your new messenger.
When downloading/uploading close all other programs.
I suggest you download and run ccleaner first before you proceed
further. Run it through a couple of times - include "registry" from the
left hand toolbar. Do not be alarmed at the amount of files you have to
delete, especially if you do not clear it on a regular basis.
Use this path to uninstall and remove the old messenger software.
> Start > computer > local disc (C) > program files > yahoo > messenger > UNWISE.
UNWISE is the command that starts uninstall. Make sure the old
messenger folder is clear before starting to download - I run Messenger
9 with no problems although I read here its "full of bugs," that's
because its not been installed cleanly. Yahoo tell us its the best one
to operate behind a firewall.
Check in the Messenger file after uninstalling to make sure no
fragments of software remain that will create conflicts with the
Delete shortcut on desktop
Download new freeware browser - mozilla firefox
Download the version of messenger you want using firefox
When downloading from filehippo avoid the adverts and use the green arrows to start downloads