A month is not too long to do a system restore if and only if you do not have one dating back that far. However everything else you described is exactly the recommendations I would have for you. Safe mode ,admin, etc. Do you have your Windows disc? You could boot to it and do a repair on the same drive without getting rid of your software. This will restore the registry which sounds fried at this point. Or you could reinstall Windows on that separate partition as a dual boot and then save your files and work blow the primary partition away and reinstall it.

Let me know how it goes I do this for a living believe it or not…