ITunes Update gets stuck

Question

So I need to update to the newest iTunes after updating my iPod, however whenever I attempt to update to iTunes 8 + Quicktime the update starts but quicky freezes up and an error message pops up telling me that update has an invalid signature and that the computer is removing the update. Is there anything I can do to get this to update? Without the updated iTunes, I can't use my iPod (unless I can uninstall what was updated on it) and I am stuck with the song that are on it?
All help is very much appreciated.

Answer 1

After followed all this instructions the problem continues the same.
Honestly, Apple should be doing something, Ipod is an expensive toy and we shouldn't be having any problem
Completely remove iTunes and QuickTime
Note: Songs you purchased from the iTunes Store or imported from CDs are saved in your My Music folder by default and are not deleted by removing iTunes.
1. Quit iTunes.
2. Choose Start > Control Panel.
3. Windows XP and Windows 2000: In Control Panel, open Add or Remove Programs.
Windows Vista: In Control Panel, click Uninstall a program. Alternately, in Classic View of Control Panel, click Programs and Features.
4. Select iTunes from the list of currently installed programs, then click Remove or Uninstall.
5. In Windows XP and Windows 2000, when asked if you would like to remove iTunes, select Yes.
6. In Windows Vista, if your permission is needed to continue, click Continue.
7. After uninstalling iTunes, do not restart if you are prompted to.
8. If other entries were present for iTunes remove those as well.
9. In Add or Remove Programs or Programs and Features, remove any iPod Updater applications that are listed in the same fashion as iTunes was removed.
10. In Add or Remove Programs or Programs and Features, remove any QuickTime installations that are listed in the same fashion as iTunes was removed.
11. Restart your computer.
12. After the computer restarts, open Local Disk C: in My Computer/Computer or whichever disk programs are installed on.
13. Open the Program Files folder.
14. Right-click the iTunes folder and select Delete and choose Yes when asked to confirm the deletion. Note: This folder may have already been deleted if iTunes was successfully removed in steps 1-8.
15. Right click the iPod folder and select Delete and choose Yes when asked to confirm the deletion.
16. Right-click the QuickTime folder and select Delete and choose Yes when asked to confirm the deletion.
17. Delete the QuickTime and QuicktimeVR files located in the C:\\Windows\\system32\\folder.
18. Right-click on the Recycle Bin and on the shortcut menu, click Empty Recycle Bin.
19. Restart your computer.
20. Install the latest version of iTunes from http://www.apple.com/itunes/download.
Empty your Temp directory and restart
1. On the Start menu, click My Computer/Computer (or double-click My Computer on the Desktop).
2. In My Computer/Computer, open Local Disk C:.
3. Windows XP and Windows 2000: Open Documents and Settings.
4. Windows Vista: Open Users.
5. Double-click the folder that bears your username.
6. Windows Vista only: If you see an AppData folder, double-click it and skip to step 12. If you don't see an AppData folder, skip to step 9.
7. Windows XP only: If you see a Local Settings folder, skip to step 12. If you don't see a Local Settings folder, proceed to the next step.
8. Windows XP and Windows 2000: From the Tools menu, choose Folder Options.
9. Windows Vista: From the Organize menu, choose Folder and Search Options.
10. Select the "Show hidden files and folders" button.
11. Click OK.
12. Double-click Local Settings or Local folder (If on Windows Vista, you must first double-click the AppData folder). If Windows needs your permission to continue, click Continue.
13. Right-click on the Temp folder and on the shortcut menu, choose Delete.
14. In the confirmation dialog that appears, click Yes.
15. If you are unable to delete the Temp folder, close all programs, especially those in the Notification area (system tray) of the Windows Task bar shown below and repeat step 10.
16. Restart your computer.
17. Install the latest version of iTunes from http://www.apple.com/itunes/download.
Clean up iTunes installer files on the computer
You can download the Windows Installer Cleanup Utility from Microsoft, which will clean up any leftover installer files that may be causing issues with your current installation. To do this:
1. Click here first, and read the important information about the software.
2. Click the "Download the Windows Installer Cleanup Utility package now" link on that page to download a file titled msicuu2.exe.
3. Open the msicuu2.exe file and follow the prompts to install it.
4. On the Start menu, point to All Programs and then click Windows Install Cleanup; the Windows Installer Clean Up Utility window appears, listing software that is currently installed on your computer.
5. Select iTunes from the list and click Remove.
6. Click OK in the confirmation dialog that appears.
7. Repeat steps 5 and 6 if you have multiple iTunes entries listed.
8. Select QuickTime from the list and click Remove.
9. Click OK in the confirmation dialog that appears.
10. Repeat steps 8 and 9 if you have multiple QuickTime entries listed.
11. Click Exit.
12. Restart the computer.
13. Install the latest version of iTunes from http://www.apple.com/itunes/download.
Download QuickTime Standalone Installer
Try downloading and installing the standalone version of QuickTime from http://www.apple.com/quicktime/download/. Be sure you download the version that does not include iTunes.
Disable other conflicting software
In Windows, some background processes can cause issues for other programs and processes. These conflicts can prevent applications such as iTunes and QuickTime Player from installing. See "Using MSCONFIG to troubleshoot conflicts in Windows" for assistance disabling conflicting processes.
Make sure your folder names don't contain strange characters