You might be able to use the recovery console, and copy the file back from the windows CD or another computer, but it’s odd that the repair didn’t put it back for you.
If windows isn’t running, then avast isn’t running. I can’t think of how avast would be preventing the file from being copied to the system during a repair…
How about the recovery console that I mentioned before? Could you possibly copy the file back?
I’m guessing that safe mode does the same? If not, you might try get the file copied back from there. I’m assuming that safe mode is pretty much out of the question at this point though. Userinit has much to do with the login process.
Hopefully, there will be an easy way to get this remedied. However, from what I’ve read on the forum, if there is something important in the virus chest, and you can’t login to windows to restore it, it makes things quite difficult…