As a start and to rule out format errors up front, boot the Windows 7 installation media to diskpart and run the
clean command, once the clean finishes, exit diskpart and use the Windows 7 installer to create and format a single 100GB partition to do the install to.
If that does't work, after another
clean, use diskpart to create, format and mark
Active a single 100GB partition to see if that works, use
Step #
2 in the SSD/HDD tutorial for reference.
Once the clean finishes, exit diskpart and use the Windows 7 installer to create and format a single 100GB partition to do the install to and be sure to post back with any further questions you may have and to keep us informed.
After you have
copied out or made
back-ups of the data you need to external media and want to start fresh with a
clean installation or clean install with an
upgrade version of Windows 7 have a look through the information below and be sure to post back with any further questions you may have and to keep us informed.
It may be a help to over-write the HDD Master Boot Record (MBR) before you start any other procedure using the diskpart
clean command, rather than the clean all; it takes just seconds to complete so you will have "unallocated" space to use either the Windows installer to create and format the partition(s) or use diskpart to create them, however you choose.
If you want to completely wipe / over-write the entire Hard Disk Drive of any possible format errors, malware infection, for security purposes or just to get the best possible place to install Windows to, have a look at these tutorials.