Hi Sharon,
IaStorAV.sys is a third-party device driver or system file that is necessary to allow hardware to communicate with Windows operating system.
In most cases, this problem can be caused by hardware, firmware, memory, or driver issues.
As an initial troubleshooting step, we suggest running a full antivirus scan using Windows Defender or your antivirus software and see if it will detect any infections.
Also, for any system file corruptions related to iaStorAV.sys, we recommend running the System File Checker tool to scan and repair missing or corrupted system files.
Update us with the outcome so we can provide further assistance.