I attempted to load/Upgrade my Vmware 4.x to 5.5. After a few struggles, I finally completed the installations. These instructions may assist you in completing the process with minimal issues.
Place the DVD into your server
2. The installation files will continue to load.
3. You will see the the OS VMKernel is loaded.
4. The welcome screen will appear after the load.
5. Press F11 to Accept the License Agreement
6. At this point you will need select a primary disk which will hold the VMware ESXi files.
7. You can retrieve information here by selecting F1
8. If files already exist (As in my case) you will have an option to either upgrade and keep the old files or select a clean install. The Clean install will overwrite all files.
9. Select the language.
10. Set the password for the “root” user account. The installer does not enforce or warning you about complexity, However, I would recommend a complex password. It is ok to select a basic password but remember to change it later.
11. You may receive warnings if you are working on a very old server or a server who settings have not been correctly configured.
12. Finally, you are given one last chance to abort the installation.
13. The the installer will copy the software to the disk/volume/LUN you selected earlier.
14. At the end of the install pressing [ENTER] will trigger a reboot – be sure to eject or close any mounted .ISO or physical DVD in the server.
15. After the reboot is completed, you should see the VMware ESXi . This allows a number of post-configuration tasks to take place, and also be used as one method of troubleshooting an ESXi host if become unresponsive. You will have to setup the correct network and IP configuration after the install is completed.