Try booting into safe mode, then select start with last known good configuration. You could have a corrupted master boot record (mbr) or the HD may have gone bad. Do you have your OS disk? If you do, you can try a repair install of windows. Start to make a list of the things on the drive you may want to keep as a clean install of windows and or a new HDD may be required.
Is this a HDD or SDD? run 'chkdsk' from either window's safe mode or recovery console. Try this link for command instructions: http://technet.microsoft.com/en-us/library/bb491051.asp.... Also if you can boot into windows try reading the S.M.A.R.T. settings with a utility that'll report the drive's health.
*edit* oh ya, is that a blue screen or Bios Post message?