That version should be OK. When you upgraded did you disable McAfee temporarily? Actually I've found when doing an upgrade as big as that (Service Pack for example) I've always uninstalled McAfee, then reinstalled afterwards.
You could try uninstalling, check if your apps work, if not then something went wrong with the upgrade to 8.1 and you need to ask on a Windows help forum.
Once uninstalled run the MCPR cleanup tool and reboot.
Then reinstall from your online account.
I too upgraded my 8 to 8.1 and haven't seen the issue but mind you, I have McAfee Total Protection Beta installed on that, so can't really compare.
If the above doesn't help I suggest you open a case with Technical Support, Free by phone or online chat and linked under Useful Links at the top of this page.
Escalate the case if no luck at first.