windows installer error help

I have been searching for ways to repair my windows installer. Here is the error...
"The Windows Installer
Service could not be accessed. This can occur if the Windows Installer is not
correctly installed. Contact your support personnel for assistance".

Here are two attempts below:

Here's the easy steps:
1. Go to a Windows Vista (Any Version) computer that has the Windows
Installer service running correctly and run regedit(Start-Run-Regedit)
2. Go to the location
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\msiserver
3. Right click on this key and select "Export" and save the key to a Flash
Drive or other.
4. Run sfc /scannow on the damaged Vista computer - you won't need the
install disk as it goes to backup files on your HD. Do not reboot when
complete
5. Double click saved .reg file from working machine and import registry
settings into damaged Vista computer.
6. Now reboot and try to install/uninstall



2. "Below is the Registry setting that controls the Windows Installer Service.
Have a look in your Registry and see if your dword is set to 2.
The setting of 2 tells the system it starts Automatic and is what it should
be.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\msiserver]
"Start"=dword:00000002"

Now attempt two led me to the registry where, in fact, my dword was set as "3". I have made the changes and will reboot now. My questions are these:

1. How did windows installer get damaged?
2. Can an upgrade or downgrade in OS fix this if nothing else does?


Thank you all so very much for your input.

Best,
Andy

it seems the dword adjustment had no effect. I then attempted a clean boot like so...

1. Click Start, type msconfig in the Start Search box, and then press ENTER.

If you are prompted for an administrator password or for a confirmation, type the password, or click Continue.

2. On the General tab, click Selective Startup.

3. Under Selective Startup, click to clear the Load Startup Items check box.

4. Click the Services tab, click to select the Hide All Microsoft Services check box, and then click Disable All.

5. Click OK.

6. When you are prompted, click Restart.

7. After the computer starts, check if the issue is fixed.

If your issue is resolved after performing Clean Boot, then follow the steps mentioned in the following KB article to narrow down the exact source:
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7

Also, see the section on how return your computer to a Normal startup mode by following the steps under “Reset the computer to start as usual”, after performing the clean boot troubleshooting.

Is there anyone who may have a solution?

Thanks,
Andy