my question would be how exactly did you remove McAfee because it takes a special program to do the full removal if you did not use their special tool then I would get this and use it to fully remove all aspects of McAfee which can definitely leave a lot behind and cause conflicts. Using AppRemover you will definitely want to get rid of the registry cleaner and not be using that. You can also install malwarebytes and update it and use it in full scan mode, use it weekly, it will not interfere with AVG. Malwarebytes' Anti-Malware (Win) - Detecting and Removing Malware

Microsoft Security Essentials has a setting in the rear that helps somewhat for faster scans.. I set mine to limit use to 100% of cpu ... default, if I recall right, was 30%. MSE no matter what the cpu % is set .. seems to always give other programs 1st priority, and sits & waits for the cpu to be unbusy for its little fun fast time slices. Thats probably why it seems to take so long to finish an update or scan. The newer version seems to update fractionally much smaller definition downloads. Which is nice when you push a manual scan!

I do not know if what you are seeing is the real shield or if you have one of the fake AV infections which produces a fake shield it sounds like you do have one of the infections. Run malwarebytes asap and post the scan results here please. Please download Malwarebytes' Anti-Malware to your desktop. * Double-click mbam-setup.exe and follow the prompts to install the program. * At the end, be sure a checkmark is placed next to Update Malwarebytes' Anti-Malware and Launch Malwarebytes' Anti-Malware, then click Finish. * If an update is found, it will download and install the latest version. * Once the program has loaded, select Perform full scan, then click Scan. * When the scan is complete, click OK, then Show Results to view the results. * Be sure that everything is checked, and click Remove Selected. * When completed, a log will open in Notepad. Please save it to a convenient location. The log can also be found here: C:\Documents and Settings\Username\Application Data\Malwarebytes\Malwarebytes' Anti-Malware\Logs\log-date.txt

wait you don't have to take those off just turn them off while you try to get AVG to install and work. They are all fine good programs and should be on the pc. I would bet some of Norton may still be hanging in there causing the problem, so definitely use their removal tool for the version of Norton that she had that should clear up most of it. then go to right click start then explore in the tree> program files see if there is still a folder for Norton if so delete the entire Norton folder, anything you see labeled Norton or Symantec should go. You did not do anything wrong sometimes things just have conflicts and especially with Norton. So do the removal of that then just turn off those programs and try AVG again. The reason I suggest using the method in the AVG faq is that it keeps it from installing some of the extras that have caused problems on some pcs. It is a much slimmer version. You are doing a good deed! You are helping someone ,that is always a good thing. As I said it may require doing an add remove on AVG then reinstalling it, that is why it should be disconnected from the internet since you will be with out protection while AVG is not working. If AVG continues to fail you could try AVAST free, I use it on one of my pcs. avast! 4 Home Edition - FREE antivirus the install and user guide are on that same page off to the left. I do not use Vista so if anyone is aware of any conflict issue that I don't know about hopefully they will let us know.