Found this advice elsewhere :-
If you disable system restore then your AntiVirus will be able to clean the trojan from the system restore archive. But I think this process will delete all previous system restore points. You can then, if you are confident that the trojan is completely erased, create a new restore point after re-enabling system restore.
Alternatively you may be able to go back to a prior system restore point i.e.the day prior to getting the trojan and it may do the trick for you.
If you do not understand then seek further advice ... (I use Win98se so not into 'restore points' etc)
P