You can check your version by opening Security Center (either right-click the taskbar icon and select open, or double-click it) then click "About" at the lower right of the open window.
System restore will always destroy or at least corrupt the installation. If updating it manually (right-click - Update) fails then follow these instructions:
1. Uninstall all McAfee programs through "Add or Remove Programs" in Windows "Control Panel".
2. Use the MCPR tool, see this article:
How to remove supported McAfee consumer products using the McAfee Consumer Products Removal tool (MC... This will remove all McAfee remnants from your computer. (you must have Windows Vista, XP or 2000 SP4 to use this tool)
3. Launch Windows Explorer and delete all McAfee files in "Program Files" but especially in "C:\Document and Settings\<user>\Application Data" and "C:\Document and Settings\All Users\Application Data". You have to set Windows Explorer to show all hidden files and folders (Tools > Folder Options > View tab). Just delete the McAfee folders even if they are empty in all the "Application Data" folders. Can be more than one!
In Vista: C:\Program Files, C:\ProgramData and C:\Users\yourname\AppData\Roaming
If you can't find these files don't worry. It just means that MCPR has done its job.
4. Reboot and redownload/reinstall your McAfee products directly from your account at the McAfee web site.
If that fails to help please use Technical Support Chat which is free via the link at top left of this page and ask them to escalate the issue if necessary.
This problem has got to the point where it is beyond our help and they can at least connect with your machines to see what is going on.