SubSeven is a pest to remove, the best way to recover from subseven is a reinstall from your last known (safe) backup and apply a stricter software installation policy.
Someone allready mentioned the registry
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Curr
entVersion\Run\
There are quit a few more registry entries that can autostart apps (or have them hijack on some other programs startup).
Besides that, there are more ways in windows to autostart an app.
Then subseven is widely known (infamous) thus there are many different versions/mods.
That is why I think: 'reinstall'