Media Errors and failed amrecovers

I am running an OpenBSD 3.0 box with an adaptec 2940. Connected to thisis a VXA-1 Rakpak(only 1 drive). The entire setup works beautifully fora few days, and I never get any errors when it makes the backups atnight. I test each tape by restoring a file from one of the level 0dumps(tar) the morning after. If it has been a few days, I start to geterrors and amrecover dies and this is in the log:

amrecover: Can't read file header
Also, in dmesg I get:
st0(ahc1:10:0): Check Condition on opcode 0x8
    SENSE KEY: Media Error
   INFO FIELD: 32768
     ASC/ASCQ: Recorded Entity Not Found

If I manually use mt and dd, I can see the header, which looks fine, andI can get the files if I manually use mt and dd piped to a file, thenuntar them, but those media errors bug me, plus I would like to be ableto use the tools.

I hope that some of you have an idea that will help you. I hate powercycling the server every few days.


Thanks,
Adam