I can't install Snow Leopard on my iMac 20" 20.GHz Intel Core 2 Duo with OS X 10.4.10., I can't install Snow Leopard on my iMac 20" 20.GHz Intel Core 2 Duo with OS X 10.4.10.

Are you doing the following:

Clean Install of Snow Leopard

Be sure to make a backup first because the following procedure will erase

the drive and everything on it.

1. Boot the computer using the Snow Leopard Installer Disc or the Disc 1 that came

with your computer. Insert the disc into the optical drive and restart the computer.

After the chime press and hold down the "C" key. Release the key when you see

a small spinning gear appear below the dark gray Apple logo.

2. After the installer loads select your language and click on the Continue

button. When the menu bar appears select Disk Utility from the Utilities menu.

After DU loads select the hard drive entry from the left side list (mfgr.'s ID and drive

size.) Click on the Partition tab in the DU main window. Set the number of

partitions to one (1) from the Partitions drop down menu, click on Options button

and select GUID, click on OK, then set the format type to MacOS Extended

(Journaled, if supported), then click on the Apply button.

3. When the formatting has completed quit DU and return to the installer. Proceed

with the OS X installation and follow the directions included with the installer.

4. When the installation has completed your computer will Restart into the Setup

Assistant. Be sure you configure your initial admin account with the exact same

username and password that you used on your old drive. After you finish Setup

Assistant will complete the installation after which you will be running a fresh

install of OS X. You can now begin the update process by opening Software

Update and installing all recommended updates to bring your installation current.

Download and install Mac OS X 10.6.8 Update Combo v1.1.

Be sure your computer meets Mavericks' requirements:

Upgrading to Mavericks

You can upgrade to Mavericks from Lion or directly from Snow Leopard. Mavericks can be downloaded from the Mac App Store for FREE.

Upgrading to Mavericks

To upgrade to Mavericks you must have Snow Leopard 10.6.8 or Lion installed. Download Mavericks from the App Store. Sign in using your Apple ID. Mavericks is free. The file is quite large, over 5 GBs, so allow some time to download. It would be preferable to use Ethernet because it is nearly four times faster than wireless.

OS X Mavericks- System Requirements

Macs that can be upgraded to OS X Mavericks

1. iMac (Mid 2007 or newer) - Model Identifier 7,1 or later

2. MacBook (Late 2008 Aluminum, or Early 2009 or newer) - Model Identifier 5,1 or later

3. MacBook Pro (Mid/Late 2007 or newer) - Model Identifier 3,1 or later

4. MacBook Air (Late 2008 or newer) - Model Identifier 2,1 or later

5. Mac mini (Early 2009 or newer) - Model Identifier 3,1 or later

6. Mac Pro (Early 2008 or newer) - Model Identifier 3,1 or later

7. Xserve (Early 2009) - Model Identifier 3,1 or later

To find the model identifier open System Profiler in the Utilities folder. It's displayed in the panel on the right.

Are my applications compatible?

See App Compatibility Table - RoaringApps.

Although I have come across this problem myself, it was usually solved simply by trying again. But in your case it sounds like your install media may be damaged or defective. All I can suggest is that you can try cleaning the disc using rubbing alcohol and a lint-free cloth by carefully cleaning in concentric circles starting from the innermost part of the disc and working outwards. Sometimes smears, minor scratches, etc. can make a disc unreadable. Cleaning can sometimes prove helpful. But if that does not work, then you probably need a new copy of the Snow Leopard DVD.

You should not be able to jump from 10.4 to 10.6. In other words, you can't upgrade to Snow Leopard from Tiger.