In my observation…
My 1st Attempt to install Avast 5 was unsuccessful.
This was my Protection Installed
Avast 4.8 uninstalled but didn’t run the Uninstall Utility = Today
Avg uninstalled but didn’t run the Uninstall Utility = This was installed last year before avast 4.8 installed
MBAM Pro = Today
So what ive done is 2nd installation is successful.
If you have previous Anti Virus its better to download their Uninstall Utility .
Avast 4.8 Uninstalled and Download Avast Uninstall Utility http://www.avast.com/uninstall-utility
Avg = I run also Uninstall Utility
MBAM = I Uninstalled also
Dunno if its ok to install Avast 5 in running the MBAM.
My advice if you have installed another Antivirus before Avast better Download their UNINSTALL UTILITY
In avast FAQ it is said that it will automatically detect Avast 5 in previous Avast 4.8
http://support.avast.com/index.php?languageid=1&group=eng&_m=knowledgebase&_a=viewarticle&kbarticleid=455
Now Im running fine and fully protected.
Note also after uninstalling and Removing Different Antivirus using UNINSTALL UTILITY
RESTART FIRST YOUR SYSTEM BEFORE INSTALLING AVAST 5.
I hope it helps to those who has problem.