sounds like you need a Script Trigger in the BarCode field, which will trigger that script OnObjectExit
Presumably, you have a table of these barcodes--presumably one for each hard drive. I'd add a field in that table that flags each hard drive that needs special instructions. Then code your script to check for the value in this field--which is now the same in every record that requires this care to determine whether to display the cautionary message.
That way, if you need to later add 3 more drives to your inventory that require this message, you just add the needed records with the needed "flag" value and you don't have to redefine your script to check for more barcodes.