After I installed Windows 8 on my laptop, when I want to boot into Windows 7 it always checks its hard drive, but it can get into Windows 7. How do I fix it?
I have a Asus laptop A43E with this problem...
I'm assuming you installed Windows 8 in a dual boot setup with Windows 7, as I've seen what you describe when a dual boot setup is used.
Ensure Windows 8 is set to do a FULL shutdown, and not going into Hibernation or Hybrid Sleep (I believe that it's being referred to as "Fast Startup" in the last version or two of the Win 8 previews).
Using hibernation or Hybrid sleeps will (may) leave the disk marked as dirty, as it won't be fully dismounted when shutting down using (a variation of) hibernation.
I believe these settings can be checked/adjusted in "Power Options/System Settings".
If you have installed both windows in different partitions, always make sure you don't access the installation files of the other operating system on the other partition. If you do Windows will always have to check the disk first. Check out this forum on Disk Checking in windows.