McAfee relies on Internet Explorer being installed, up to date and set to default settings even if it's not default, so do you have IE8 installed and are all it's add-ons up to date? Also make sure your drivers, expecially for your Internet Connection are up to date.
MSE is not compatible with other antivirus software. You could however try Malwarebytes Free from the last link in my signature below, it no longer clashes as long as you don't accept the trial and thereby install the Pro version.
Try running the Virtual Technician to see if it can sort it out. http://mvt.mcafee.com/
Support are right, a complete uninstall, MCPR cleanup (see link in Useful Links at the top of this page for the latest version of MCPR), reboot and reinstall from the online account (not any CD you may have) usually cures all problems.
If you tried that as stated and it failed then phone Tech Support and have them escalate the issue.
IE8 is installed and fully patched on one PC and IE9 on the other.
MSE was installed when McAfee had been removed and was then removed before McAfee reinstall. I understand that Malwarebytes is now compatible, but have kept it seperate, just in case.
The removal, cleanup and reinstall undertaken used new downloads through my account. It has been done several times.
It was IMPOSSIBLE to run Virtual Technician on the PCs because of the problems and issues. When an application - such as Explorer was chosen, it could take up to 2 minutes to start running.
One comment from the support adviser was "are you on a dial up connection" becasue he was seeing such a slow response from the PC - I have a VDSL2 service!
Hmm, yes your connection shouldn be the problem. It's difficult to say really when one isn't there, that's where support can shine if they can connect with the machine and troubleshoot it.
Off the top of my head all I can think of now are...any competing software installed, even remotely competing? Any Daemon tools, or Alcohol 120% installed? They've been known to clash.
Also when the software is installed is it set to default settings...meaning you don't have the firewall in lock down? Plus programs that need it should have full permission in Firewall.
Those stock answers from suppoort tell me you were talking with the 1st level who always ask the same questions but there are many levels of support and you can ask for the escalation.
Do you get McAfee from BT or from McAfee direct? It is just possible that the former isn't delivering the latest version as they often sit on patches for an inordinate time.
No "competing software" and it just suddenly happened on a Monday morning. A Level 2 tech used MSCONFIG to disable certain processes at start up - but that did not clear it.
It has gone to support level 2.5 and I am waiting for a call bak fro the "Research Team" -requested for Friday, then Yesterday, and now being told Wednesday evening.
The Windows firewall is set to default during install - as it always has been. But suddenly an eror will appear saying Windows Firewall is OFF, and attempts to turn it on fail.
The software is from McAfee directly.
The two PCs use the same switch, router and hub but cannot see each other and are not grouped together so cross infection is unlikely. The other PCs are using the same connectivity but neither run McAfee AV and do not have any problems.
I agree cross infection is unlikely in such a setup. Well the call back sounds promising, at least something is happening which will hopefully sort it out. Other than what I already said I can't think of anything else right now, other than Windows Firewall turning off is normal when you try to install 3rd party firewalls. If it's refusing to turn on with no 3rd party software installed then I would suspect infection first of all. If you can, follow the Hijackthis suggestion at the bottom of that last link in my signature, at least asa precaution, tro see if one of those independent forums can see anything amiss.
The Windows Firewall problem occurs when McAfee firewall is OFF or not installed.
One of the Level 2 Techs spent around 4 hours logged on to one PC ... with occasional calls to me to select the user account after a reboot.
I also believe that he ran Hijackthis and took a copy of the log/output.