Ubuntu installer fails to find partitions [SOLVED]

Question

FINAL EDIT: In order to make this work you should back up all your partitions to a different hard disk. You will lose all your data on the disk and need to make the partitions anew. Run ubuntu from a USB stick. Use your favourite tool to zap the GPT table. Delete all the partitions. Install your operating systems. Put your backups back.

Not my first time installing ubuntu but my first time installing 16.04.4 and first time installing on this laptop. I ran into the problem that while the installer could find my harddisk it does not show any partitions on it. I opened up gparted and created the required partions myself but the installer still fails to see the partitions while I am able to browse them when running ubuntu from the USB-drive. I added a link to the screenshot of both gparted and the installer. It should become a dual boot with windows 7 and it is on a HP Elitebook 8570w.

Thanks in advance!

EDIT: I tried to install with version 16.04.1 but ran into the same problem. I repaired my windows partitions as sudodus suggested. It still didn't work. Eventually I booted Ubuntu from the installation disk and using the terminal (gdisk -l /dev/sda ) I discovered that both MBR and GPT was present. I tried to fix this with fixparts /dev/sda but this claims it will overwrite my entire disk which seems a bit excessive. Anybody any ideas how to fix this?

EDIT2:

ubuntu@ubuntu:~$ sudo gdisk -l /dev/sda
GPT fdisk (gdisk) version 1.0.1

Partition table scan:
  MBR: MBR only
  BSD: not present
  APM: not present
  GPT: not present


***************************************************************
Found invalid GPT and valid MBR; converting MBR to GPT format
in memory. 
***************************************************************

Disk /dev/sda: 976773168 sectors, 465.8 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 5C4DD7BD-D25B-44E3-9FFA-DAEBF009F14B
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 976773134
Partitions will be aligned on 2048-sector boundaries
Total free space is 4206573 sectors (2.0 GiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048          616447   300.0 MiB   0700  Microsoft basic data
   2          616448       835876863   398.3 GiB   0700  Microsoft basic data
   3       940734464       972572671   15.2 GiB    0700  Microsoft basic data
   5       835878912       924348415   42.2 GiB    8300  Linux filesystem
   6       924350464       940734463   7.8 GiB     8200  Linux swap

After which I ran fixparts:

ubuntu@ubuntu:~$ sudo fixparts /dev/sda
FixParts 1.0.1

Loading MBR data from /dev/sda

MBR command (? for help): ?
a   toggle the active/boot flag
c   recompute all CHS values
l   set partition as logical
o   omit partition
p   print the MBR partition table
q   quit without saving changes
r   set partition as primary
s   sort MBR partitions
t   change partition type code
w   write the MBR partition table to disk and exit

MBR command (? for help): w

Final checks complete. About to write MBR data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!

Do you want to proceed? (Y/N): 

So indeed the GPT table seems to be there but I fail to see how I can remove it without having to format all my existing partitions.