Was Win 7 running normally and then started doing this? Have you added any new devices?
I used to get a message something like that when I tried to boot into Vista with my modem enabled. If you can get into safe mode, perhaps you could find a device you could disable to check if it was causing the problem.
You might also set msconfig to show "OS boot information" under the boot tab. You could watch the boot sequence to see if a driver was having problems.
Also you could make a Boot log and check it from safe mode. Tell it not to overwrite previous, if you can.