Gaz,
I'm unclear if you are running both MaCafee and MSE concurrently? We see lots of problems in systems running MaCafee - when we see these problems, they are almost always solved by installing MSE instead.
I would recommend uninstalling MaCafee completely, installing MSE and then doing this:
1. Click Start

2. In the search box, type
cmd
3. In the list that appears, right-click on cmd.exe and choose
Run as administrator
4. In the command window that opens, type
sfc /scannow and hit enter.
Report the output once it finishes.
Regards,
Golden