Ok, so I'm running Windows Vista.
I was having the same problems with the Instance Config Wizard as all of you, and I just don't seem to be getting it.
Here's what I've done:
1. Disabled UAC.
2. Rebooted the machine.
3. Opened a port in the Windows firewall as instructed by the
http://port25.technet.com file "MySQL_Windows.pdf".
4. Uninstalled version MySQL 5.0.5 (from previous installation that was preventing me from running the Config Wizard).
5. Reinstalled MySQL 5.0.5 and at the end of installation selected to launch the Config Wizard (which never successfully launched).
6. Tried to manually launch the Config Wizard and received the dialog box "The application has failed ti start because its side-by-side configuration is incorrect. Please see the application event log for more detail."
This is the same error I was receiving when I installed MySQL the previous time before I went through disabling UAC and opening the Firewall port.
To let you all know, I haven't tried to install a previous version of MySQL because I cannot find a previous version that has the .EXE file that is required for Windows (file hippo only has an Essential previous version).
Please help.
Thank you in advance.