windows installer maintenance mode via msiexec msi

I just began to test .msi installations on Vista and I know very little. I can double-click a .msi installation written using InstallShield 10.5 and it installs ok. But when I double-click it again or run it using msiexec in order to go into Maintenance Mode I get a security error saying it isn't allowed as I don't have the correct privileges. Yet, I have Administrator privileges which allowed me to install it in the first place. I can only get into Maintenance Mode if I go through the Control Panel. Why can't I get into Maintenance Mode via msiexec or double-clicking the .msi like I can on previous operating systems? Is there a security policy I can change?
Also, will I be able to perform minor updates of the product I installed as I have before when I run the msiexec command with the REINSTALL and REINSTALLMODE parameters?

I'm still testing our legacy installations and our Vista system has been reloaded and now I can get into Maintenance Mode via msiexec or double-clicking the .msi. I don't know what changed. Supposedly the Vista build was the same - Beta 2 build 5384. If anybody knows what might have caused the previous problematic behavior I'd still like to know.
I still have an issue with performing a minor update using a full .msi. When I enter the following from the Run command or from a VBScript:
msiexec /i "c:\test.msi" REINSTALL=ALL REINSTALLMODE=vomus /qb
I get the following error:
"The system administrator has set policies to prevent this installation"
In order to successfully install the update I figured out I can do one of two things:
1) Enable the AllowLockdownBrowse policy (Enable user to browse for source while elevated). 2) Right-click on the Command Prompt and "Run as Administrator".
Are either of those the methods of accomplishing this task the correct way of doing it? Is one preferred over the other? Is there some code somebody can point me to that I can put in a VBScript that will verify/ask the user for Administrator credentials and then when the script runs msiexec the .msi will inherit the Administrator credentials and install? Is there another way? Is there a Vista bug that should have automatically asked me if I was sure I wanted to perform the update instead of just failing?
Answers to any of my questions will be appreciated.
Thank you, Scott
"Linden" wrote:

I just began to test .msi installations on Vista and I know very little. I can double-click a .msi installation written using InstallShield 10.5 and it installs ok. But when I double-click it again or run it using msiexec in order to go into Maintenance Mode I get a security error saying it isn't allowed as I don't have the correct privileges. Yet, I have Administrator privileges which allowed me to install it in the first place. I can only get into Maintenance Mode if I go through the Control Panel. Why can't I get into Maintenance Mode via msiexec or double-clicking the .msi like I can on previous operating systems? Is there a security policy I can change?
Also, will I be able to perform minor updates of the product I installed as I have before when I run the msiexec command with the REINSTALL and REINSTALLMODE parameters?