This vaguely related:
I recently uninstalled AVG for a Windows 7 machine using their own removal tool --
after it had removed AVG, I got this message:AVG sntivirus possible false positive report this morning on win 7 system files
which (literally translated) says:
|An incompatible anti-virus discovered:
Microsoft Security Essentials
We strongly recommend you uninstall it, so that your computers performance will not be adversely affected.
Note I have nothing against AVG, but ironically, on this particular old laptop with crappy cpu, I was removing it because
it was slowing down things too much.