I first installed Windows first, after it I installed Linux so that both OSs functioned on the same computer, but were located on different partitions of the disk. Shared a disk using acronis disk director suite. Everything worked and the GRUB bootloader displayed both OSes when the computer was turned on.
But something happened. In my opinion, I changed the main active partition with the same acronym. After that, the same algorithm for installing two operating systems no longer works. Now, after installing Windows 7 and Linux (ROSA), when you turn on the computer, the GRUB boot loader displays only one OS that was installed last. Although both operating systems were installed on different partitions.