bootbank cannot be found at path /bootbank

Hi

In vCenter for one of the ESXi server I am getting  error as "bootbank cannot be found at path /bootbank"

Reboot is temporary solution for this.

Out of two devices there is none USB device at boot time

vmhba32 usb-storage link-n/a usb.vmhba32 () USB

And below is the error details :-

SCSI Level: 2 Is Pseudo: false Status: dead timeout

Is RDM Capable: false Is Removable: true

Can some one please suggest permanent solution if any.

Thanks &  Regards