I'm running Vista and have (I thought) recently got rid of a back door trojan virus by deleting startup items which had N/A as their title. Seems to have done the trick, but when I ran Malwarebytes Anti-Malware prog scan, I still appear to have on file in a folder under software entitles 'Cerebrus'. The remaining file is called (Default) REG SZ. Every time I delete the folder, it re-names itself 'Classes' and the aforementioned file cannot be removed. If I try to find the folder in Explorer it doesn't show up. Any ideas?
Find the undeletable keys using regedit, select the folder on the left window pane.
Right click the folder and scroll down to select “Permissions”. In the section marked “Permissions for Administrators” make sure that under “Full Control” that the “allow “tick box is ticked, click OK.
With the folder still highlighted, right click on the folder and select delete or just press the delete key on your keyboard to remove the entry for good.