After extensive troubleshooting, the core issue appears to be an InnoDB log file size mismatch. The error log revealed:

InnoDB: Error: log file .\ib_logfile0 is of different size 0 56623104 bytes
InnoDB: than specified in the .cnf file 0 106954752 bytes!

This occurs when previous MySQL installations leave behind incompatible InnoDB log files that don't match the current configuration.

Here's the definitive fix that worked after all other attempts failed:

1. Uninstall MySQL completely
2. Delete these directories:
   - C:\Program Files\MySQL
   - C:\Program Files (x86)\MySQL
   - C:\ProgramData\MySQL (hidden folder)
3. Remove any my.ini or my.cnf from Windows directory
4. Clean registry entries using CCleaner or similar tool
5. Reboot
6. Install MySQL 5.5 again
7. Before starting service, delete any existing ib_logfile* files:
   del /f /q "C:\ProgramData\MySQL\MySQL Server 5.5\data\ib_logfile*"
8. Start configuration wizard as Administrator

If the wizard still fails, configure manually:

# Create minimal my.ini configuration file
[mysqld]
basedir=C:/Program Files/MySQL/MySQL Server 5.5
datadir=C:/ProgramData/MySQL/MySQL Server 5.5/data
port=3306
innodb_log_file_size=48M

Then initialize and start manually:

cd "C:\Program Files\MySQL\MySQL Server 5.5\bin"
mysqld --initialize-insecure
mysqld --console

For future troubleshooting, these commands are invaluable:

# View MySQL error log in real-time
mysqld --verbose --help
mysqld --console > mysql_debug.log 2>&1

# Check Windows Event Viewer for service errors
eventvwr.msc

To avoid similar issues:

• Always uninstall properly via Control Panel
• Use MySQL Installer rather than ZIP archive
• Keep data directory backed up before upgrades
• Consider using XAMPP/WAMP for development environments

As a last resort, MySQL 6.0 alpha worked in this case, though not recommended for production. The key takeaway is that InnoDB log file corruption was the root cause, not Windows permissions or ports as initially suspected.

After battling with MySQL installation on my Windows 7 x64 Enterprise system, I discovered the service would consistently fail with Error 1067. The configuration wizard would hang indefinitely at the "Start Service" step, leaving me with a non-functional database server.

Before identifying the root cause, I exhausted these common solutions:

• Disabled firewall and antivirus completely
• Tried both 32-bit and 64-bit MySQL 5.5 installations
• Verified no port conflicts (3306 was available)
• Confirmed no residual MySQL files in Program Files directories
• Ran all installers as Administrator with UAC disabled

The key to diagnosing this was forcing MySQL to output error messages to console:

mysqld --console

This revealed the actual error:

InnoDB: Error: log file .\ib_logfile0 is of different size 0 56623104 bytes
InnoDB: than specified in the .cnf file 0 106954752 bytes!
101221 13:57:28 [ERROR] Plugin 'InnoDB' init function returned error.

The error indicates a mismatch between the InnoDB log file size declared in my.ini and the actual ib_logfile0 size. This typically occurs when:

1. Previous MySQL installation left corrupted log files
2. Manual configuration changes weren't properly applied
3. InnoDB parameters were altered between installations

Here's the step-by-step fix that worked:

1. Uninstall MySQL completely
2. Delete these directories:
   - C:\Program Files\MySQL
   - C:\Program Files (x86)\MySQL
   - C:\ProgramData\MySQL (hidden folder)
3. Remove any my.ini files from Windows directory
4. Install MySQL fresh
5. Before starting service, edit my.ini:
   [mysqld]
   innodb_log_file_size = 48M
   innodb_buffer_pool_size = 203M
6. Run these commands as Administrator:
   mysqld --remove
   mysqld --install
   net start mysql

If the above doesn't work, you can completely reset InnoDB by:

1. Stop MySQL service
2. Delete ib_logfile0 and ib_logfile1
3. Delete ibdata1
4. Start MySQL service (it will recreate these files)

To avoid similar issues:

• Always uninstall MySQL completely before reinstalling
• Use consistent InnoDB parameters across installations
• Consider using MySQL Installer instead of manual ZIP install
• Document all configuration changes