Windows start up repair cannot fix this problem automatically.
A couple days ago my computer which is running windows 7 pro 64 bit started rebooting after it got to the windows logo after turning on the computer then giving the option of using start up repair or starting normally. I clicked the repair option and like the title said it cannot solve the problem. I haven't really tried anything yet so any advice is welcome EXCEPT reinstalling the OS. I have hundreds (literally) of gigs of data on that computer and cannot afford to lose all of it. Also booting in safe mode will not work either.
Have you tried to use "last known good configuration" instead of safe mode?
As the computer is booting and it passes the bios checks, press F8 a few times and you will be given many more options for starting windows 7... Try Last know good configuration and that might do it. Usually when you get random resets it is something that has been recently installed or a piece of hardware that windows isn't liking.
Take out any new hardware, and if that doesn't work,
If you can't lose the information, I would say to take out the hard drive and hook it up to another computer or put it in an external enclosure and use another computer to hold your data for a while.
Is the windows installation and all your data on the same partition? If not then just re-installing windows on the main partition shouldn't be a problem as it shouldn't mess with the partition the data is on.