Alok - Hi,
So (slightly confused) I have AVG Zen 1.125.2.55495 installed - Free.
On the "home page" when I open it from the toolbar there are 4 options:
1. AntiVirus page Free (Protected)
2. PC Tuneup (not tuned up)
3. HMA!PRO VPN (not installed)
4. Web Tuneup (Enabled)
Pressing the PC Tuneup I get the "Fix your performance" page and there's a button that says "Get it FREE". Hitting that button it goes through an installation process that fails (as previously stated). So no need to uninstalled - it hasn't installed!
So, is this a free trial that isn't loading properly, or is the PC Tuneup page wrong?
I am also getting a number of "freezes" when nothing happens for several minutes. During these periods the HD light flashes occassionally but not excesively indicating normal HD access and the CPU using is low. Is AVG Zen busy at this time?
The good news that everthing seems to run faster without Microsoft Security Essentials! 
Hello David,
We are sorry for the inconvenience caused.
Are you using the Trial or paid version of AVG TuneUp?
I installed AVG Zen two days ago and decided to install the AVG Tuneup package today. It failed to install with a error code 0xC0070641. I have also noticed that the laptop at times runs very slowly despite the fact that the CPU appears to be fairly idle (4 to 10%).
The previous Virus Checker was Microsoft Essentials which is no longer supported and was uninstalled using Windows Uninstaller before installing AVG.
Operating system is Windows Vista and the machine is a DELL inspron 1525 dual core.
Hello David,
We would like to like to inform you that we do not have Free version of AVG PC Tuneup. You can continue using AVG Free protection and uninstall AVG PC Tuneup expired version if you have installed.
Thank you.
Hello David,
We are sorry for the inconvenience caused.
Are you using the Trial or paid version of AVG TuneUp?
Thank you for the detailed information.
If the PC TuneUp says as not tuned up then it means that the AVG PC TuneUp is installed but it didn't tuneup the PC.
You have mentioned that by clicking on the PC TuneUp you get the get it free option which is for installing the program.
We request you to check on the control panel uninstall program window and provide the list of AVG programs mentioned on it.