It does nothing to the system time but there is a firewall setting to allow Network Time Protocol (Port 123) which you may have to enable.
Assuming you are talking about the home products double-click the taskbar icon to open SecurityCenter
Click Advanced Menu (bottom)
Click Configure (left)
Click Internet & network (top left)
Click Advanced (right)
Click System Services (left)
Check that item in the list and click Apply and then OK and exit SecuritCenter. It should be OK but you may need to reboot for it to take effect.
Moved to Personal Firewall Plus 10.
You don't get a sub menu on the left when you click that Advanced button over at the right?
Than I suggest you contact Technical Support Chat. (McAfee Support top of page > Home and Home Office Support).
Hi. Guess what happened when I clicked the 'e-mail and chat' help. The McAfee installed "Virtual Technician" an then scanned my PC. It appears to me that, because it did not find any problem, no link was provided for further help. Only option was 'help with fee'. I will replace McAfee with other program. Before I switched to McAfee I was using Avast pro and had no time/date related problem but it tended to give faulse positives. In the past I used bitdefender with good results.
Thank you for your help.
Chat support is free, you must have missed that option. However if you've decided to go with something else, that's your prerogative. Good luck.