Hello Milosss, welcome to Seven Forums!
It maybe help to do a complete wipe of the Hard Disk Drive / Solid State Drive and then start the installation process again, have a look at
Step One of the
Optimize tutorial below; after you have
copied out or made
back-ups of the data you need to save to external media,
then boot the Windows 7 installation media to do the wipe
secure erase to the HDD / SSD and be sure to post back with any further questions you may have and to keep us informed.

Whether you use diskpart to run either the clean all command to completely wipe a HDD / SSD or just the clean command to remove the format configuration data and don't use diskpart to create at least a single partition to do the installation to, letting the Windows installer do the format, the new Windows 7 System Reserved partition will be automatically issued, if you want to make your own decision whether this partition is added, study these two (2) options below.
- If you do not want to create the new Windows 7 "System Reserved" partition use the outline in Step Two #2 to create, format and mark Active a single 100GB partition to do the installation to.
- If you do want to create the "System Reserved" partition use the outline in Step Two #3 to create, format and mark Active the System Reserved partition and then create and format the 100GB partition to do the installation to.
Either way, running the
clean all then creating and formatting the partition(s) using diskpart will get you the best possible space to do a
clean install of Windows 7 to; you can always
extend the Windows partition to include the remaining unallocated space on the HDD / SSD or
create additional Primary partitions or an
Extended partition after the installation completes if you choose.
SSD / HDD : Optimize for Windows Reinstallation DISKPART : At PC Startup