If you have vista and Live onecare and you like MP!L to work you will have some work.
Windows Live OneCare detects MP!L as High risk and there for you will get one of two:
1. Installing will not work (You will get - " an error occurred while installing messenger plus! " messege).
2. Your Messenger (if you have it before) will not work (You will get - " the application failed to initialize properly (0x0000022) " messege).
What can we do?
First, if you will do what I did, you will have Live messenger and MP!L up and working in no time, you will need an Administrator Acount to apply this work arround, so just reade on...
1.Installing
Open LOC panle and go in to Settings > Viruses and Spyware and put (for now) in Off.
Now you can install MP!L as we know it, after you are finsed remember to re activate the Viruses and Spayware by selecting On.
For now you will see that Messenger and MP!L is working but! as you restart....
2. Work around the crauses
When you try to open the Messenger it stopes and there is "no" way to open it but to uninstall MP!L?
You don't need to uninstall!!! just do as i did:
Open LOC panle and go in to Settings > Viruses and Spyware > Exclusions... and add two folders by clicking on 'Add Folder...'
Add The Messenger Plus! Live folder and the Messenger it self (you will find them under Program Files, and then ok and ok.
After that you will have you MP!L working as we know it, if after a restart you can't see it try to reinstall the MP!L one more time and that will do the job.
My system runs Vista Unlimeted, Live Messenger 8.1, MP!L 4.10.250
Hope that will work for you two and you will be up and running in no time.
Patchou
From what i found out the problem is that write prevliges, MP!L didn't have them or somting like that, i'm sure that you will find a way to fix that, hope that my post will help you.
p.s
Sorry about my english...