Found a Symantec doc that states that this message can be caused if the tape drive cannot read the MRS Stripes
http://entsupport.symantec.com/docs/230206
Then found an HP Document that describes MRS:
Media Recognition System (MRS) is a method where pre-defined stripes are placed at the beginning of the media to identify the media. The MRS stripes are read to determine if the media is of data-grade. Data-grade media should be used in SCSI streaming devices since it is of the required quality and consistency to be used to store data (i.e., audio/video grade media should not be used).
I then found another HP document that states
Media Recognition System
The Media Recognition System (MRS) enables drives to identify DDS-grade media. DDS MRS cartridges have a series of stripes on the transparent leader at the beginning of the tape. HP drives can be configured to treat non-MRS tapes as write-protected. In other words, the drive will only be allowed to read non-MRS cartridges, not write to them. DDS-1 MRS tapes can be recognized by the logo shown in the illustration above. MRS is used on all DDS-2, DDS-3, DDS-4 and DAT 72 tapes with the logos shown above.
Cartridges with the old DDS/DDS-1 logo are in no way inferior; they simply do not carry the stripes on the leader tape, so the drive cannot recognize them as DDS. All DDS-1 cartridges produced from early 1993 should have the Media Recognition System stripes.
As such are you using old DDS-1 tapes without the logo showing they also have MRS?
To see examples of the logos check out the complete HP document:
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&taskId=115&prodSeriesId=63916&prodTypeId=12169&objectID=lpg50457
If you are not using old DDS-1 tapes then this looks like a hardware/media issue, not a Backup Exec issue so I would talk to your hardware vendor - and yes I have noted that in your original message you have indicated that this only happened since moving to BE 2010 - however I suspect that we finally implemented a warning message that identifies that SCSI condition - instead of ignoring it.