How to fix computer with a Virus(es). The Operating System is Windows7 Home Edition.Computer is a Lenovo?

There are a number of Win32 PUP's that make Ads keep popping up for of all things Computer Virus Software and Computer Repair Companies to fix the troubles with it.
I have run the Avast Anti-Virus and it says there are no problems found. I have even tried setting it into Safe Mode with Networking and without. The problem is still there. I did 2 times a Boot Time Scan and found a total of 4 Win32 PUP Viruses. The same one twice. When i try to install Malewarebytes the Ads pop up and prevent me from doing the installation.
What if anything short of taking the Computer to a Repair Technician or calling gone to do the fix on-line can i do to fix the problem myself?
The Computer is not mine, but belongs to a person in the Apartment House i live in. I'm an Novice at best on Computers, but i have learned a few things over the past 2 years since purchasing my own Computer. And YES i do know it doesn't make me Steve Jobs!~Winks!~

Try restoring it to an early time - Just before the problem started.

To find out where the restore icon is located go into the control panel.

Hope this has been a help.

Download hitman pro, scan and remove virus.
also you can download free super antispyware, it should pick up the virus and delete it

Download malwarebytes on another uninfected computer and change the file name before copying the file to a usb drive to stop the malware blocking the install. Most PUP's block the execution of mbam.exe

First of all- if you run ms windows- then you need ms security essentials. Let ms work for you.

Second- do you "need" windows at all? If yes- then carry on. If no- then download and install Linux Mint and forget about all these windows issues.

I have not had an OS issue since 2008- when I switched to Linux Ubuntu.

Did I mention that its free?