windows live messenger error 1601

When you try to install Messenger, you receive the following error message:

Error 1601: The Windows Installer service could not be accessed.


PROBABLE CAUSE
Note Try to install Messenger after each of the following steps.
1. To install programs on your computer, you must be an administrator on the computer. Follow these guidelines to make sure that you have administrative permissions:
If you are on a corporate network, contact the system administrator for more information about administrative permissions.
If you are on a home network, sign in with an account that has administrative permissions.
If you cannot obtain administrative permissions, have someone with administrative permissions perform the installation for you.

2. Reregister Windows Installer.
Windows Vista
a. Click Start , type %windir%\system32\msiexec /unregserver in the Start Search box, and then press ENTER.
b. Type %windir%\system32\msiexec /regserver , and then press ENTER.
If you are prompted for an administrator password or for a confirmation, type the password, or click Allow.

Microsoft Windows Server 2003, Microsoft Windows XP, and Microsoft Windows 2000
a. Click Start, click Run, type %windir%\system32\msiexec/ unregserver , and then press ENTER.
b. Type %windir%\system32\msiexec/ regserver , and then press ENTER.

Microsoft Windows Millennium Edition and Microsoft Windows 98
a. Click Start, click Run, type %windir%\system\msiexec /unregserver , and then press ENTER.
b. Type %windir%\system\msiexec /regserver , and then press ENTER.

3. Install the latest version of the Windows Installer files.
Windows Server 2003, Windows XP, Windows XP Service Pack 2 (SP2), Windows XP Service Pack 1 (SP1), Microsoft Windows 2000 Service Pack 4 (SP4), and Windows 2000 Service Pack 3 (SP3)
Visit http://www.microsoft.com/downloads/details.aspx?FamilyID=889482FC-5F56-4A38-B838-DE776FD4138C&displaylang=en .

Microsoft Windows 2000 Service Pack 2 (SP2) and earlier versions
Visit http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=4B6140F9-2D36-4977-8FA1-6F8A0F5DCA8F .
•Windows Millennium Edition and Windows 98
Visit http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=CEBBACD8-C094-4255-B702-DE3BB768148F#filelist .

4. Reinstall Messenger. To do this, follow these steps:
a. Visit http://get.live.com/messenger/overview .
b. Click Get it free or Download now, and then complete the wizard.