%fystemRoot%\system32\svchost.exe -k netsvcs
Google brings up many people with the same problem, and many having trouble actually changing the setting back, even using RegEdit.
( path HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BITS )
In my case, RegEdit would display an error about writing the correct path to the register.
The trick that finnally did it was right-clicking the BITS service folder in RegEdit, choosing Properties and changing the permissions to full control for the Administrator user.
Hope this helps someone out there!
ps: this is caused by a virus, removing the virus first would be recommended. You may want to search the registry for other occurences of "fystemRoot"