Since it looks like her computer is quite a bit older, I’d check out the hard drive and make sure its healthy. Typically, if files are corrupted, I’d expect there was an unclean shutdown or the drive has some corrupted sectors (or both, as the latter often results from the former). If that is the case, its fixable without a new drive, as the operating system can mark them as bad, losing a bit of storage space but hopefully letting the game launch without verifying.
To check your drive, you can run chkdsk by right clicking on the drive the game is installed on in “This PC” in file explorer, then going to properties->tools and then under “Error checking,” click “Check.” You’ll have to schedule the check for the next reboot, unless the game isn’t installed on the C drive.
In addition, it’s probably worth running sfc /scannow. For more details on that:
Antivirus technically could be the culprit too, but its unlikely if you both are using Windows Defender (and, for that matter, I am too, without any issues.) Also, if the RAM was going bad or the CPU was overheating, data could be corrupted during the installation and verification. However, these would cause a lot of other issues - bluescreens, crashes, freezes, etc. So, my money is on the hard drive… Old school mechanical drives get something that is vaguely analogous to magnetic “scratches” when they lose power unexpectedly in the middle of a write operation. SSDs don’t have moving parts, but similarly can get corrupted when they lose power. Dust, heat, and plain old age can also be issues for hard drives.
Source: Currently studying computer science, have worked as an assistant to a sysadmin, and have had similar things crop up on Steam games when a hard drive was on the verge of dying.