do you have access to a recovery CD ? windows installation CD?
I"m definitely not the "smartest" in this department.. I just have seen and experienced a lot of problems with computers.. and it would be just dandy if the others would chime in..
but, there are some crazy ways to get into safe mode.. one involves turning on your computer and as it's loading windows, you are supposed to pull the power plug and force it off.. (or hold the power button down if you have a laptop with battery- or just unplug the battery!)
supposedly after the 3rd time it will ask you if you want to go into safe mode.. or recovery mode..
that might be an option.. since you are dead in the water so to speak.. but i'll research more about it..