Before you do anything else, if you have any data of value on the system, disk image the hard drive in case it is failing. You can do this from numerous different bootable utility CDs, most of which can write a disk image to an external USB hard drive.
Next, if it's a spinning magnetic hard drive not an SSD, do a S.M.A.R.T. self-test on the drive. If this passes, there's a good chance the drive is OK. Do not rely on the SMART self-reported health check, this frequently reports "PASSED" on drives that're moments from total failure. Again, numerous utilities for Windows SMART testing are available.
If the SMART test passes you probably have either a damaged operating system install or file system corruption and - if there's no data of value on the system - can reformat the damaged partition and reinstall. You might want to try booting off the Windows 7 recovery disk first, as it might be able to repair the system without reinstalling. Be aware that re-installing Windows 7 or using the recovery mode of the install disk may break Windows 8 by replacing its bootloader, forcing you to repair Windows 8 before it'll boot.
You should not get file system corruption due to crashes and power-offs. If it's happening, there's something not right with the machine. If your system has an SSD it might not have proper power protection for its write-back cache and might not respect disk flush requests - this is true of many cheap consumer SSDs. Such disks can never be truly reliable, and should only be used if you keep good backups.