OK, I think I have tried everything over many hours and so its time to seek help from real people. I uninstalled Norton 360 and am unable to reactivate Windows Firewall. The Windows Security Centre keeps telling that I should do so but when I try, ultimately the Windows Firewall Service (which is on Automatic) will not start (on boot, or when I try to activate Windows Firewall, or when I go into services.msc and try to start it manually). I have run virus scans using Malwarebytes, AVG, Superantispyware and online with ESET. I have run sfc /scannow and there are no problems reported or ignored. I have all Windows Vista updates except Windows Vista SP2 as every time I get to the 100% complete notice at the very end of the long and labourious cycle during re-boot it simply reverts back to SP1. I have tried every Microsoft FixIt available for both the Windows Firewall and Update problems to no avail. I have read many posts on the Microsoft website and tried my luck at suggestions, failing only to complete Registry alterations (that apparently FixIt does anyway) because what I am told to input by posts is not recognised at the Command or DOS prompt. I have chkdsk'd (both options). My PC is running fabulously, all except I cannot update to SP2 (all other Microsoft products update fine) and I cannot reactivate the Firewall. I would attempt a Repair installation but although my optical drive is working (tested on another PC) it is not recognised on my PC (I can launch bootable disks pre Vista no prblem at all). I can do a full destructive Factory Recovery as there is an image on the hard drive. I would rather repair all faults within the current OS as I have many programs and much data. So, keeping this thread to a specific issue, can you please help me reactivate Windows Firewall in the first instance? I am happy to fiddle in the Registry, but if you want me to check preferences please be very specific as to what I write - thats more specific than Microsoft! Thanks. Its killing me.