I occasionally have this problem with an OS/2 guest under Virtualbox. I don't know where it comes from.
But you might want to play around with the switches for DANIS506.ADD or OS2AHCI.ADD (whatever you are using) to slightly lower performance (for example, for OS2AHCI.ADD, do not enable native command queueing, do not enable HW write cache etc.) so see if that makes a difference.