[NTLUG:Discuss] USB hard drive question

[Fred James]

All
Old Dell laptop (circa Pentium 4 Mobility) with two external hard drives 
(USB attached) ... been running swimmingly (for a year at least), until ...

This event has happened only twice (Tuesday and today) - lost the USB 
hard drives ... message in syslog:

May  8 11:53:44 bandaid kernel: usb 2-1: USB disconnect, address 2
May  8 11:53:44 bandaid kernel: sd 0:0:0:0: SCSI error: return code = 0x70000

... followed by thousands of lines like these ...

May  8 11:53:44 bandaid kernel: end_request: I/O error, dev sda, sector 1458647143
May  8 11:53:44 bandaid kernel: Buffer I/O error on device sda1, logical block 182330885
May  8 11:53:44 bandaid kernel: lost page write due to I/O error on sda1
May  8 11:53:44 bandaid kernel: sd 0:0:0:0: SCSI error: return code = 0x70000
May  8 11:53:44 bandaid kernel: end_request: I/O error, dev sda, sector 1458647151
May  8 11:53:44 bandaid kernel: Buffer I/O error on device sda1, logical block 182330886
May  8 11:53:44 bandaid kernel: lost page write due to I/O error on sda1
May  8 11:53:44 bandaid kernel: sd 0:0:0:0: SCSI error: return code = 0x70000
May  8 11:53:44 bandaid kernel: end_request: I/O error, dev sda, sector 1458647159
May  8 11:53:44 bandaid kernel: Buffer I/O error on device sda1, logical block 182330887
May  8 11:53:44 bandaid kernel: lost page write due to I/O error on sda1


Thank you in advance for any help you may be able to offer in figuring 
out what is going on here
Regards
Fred James

PS:  The devices sit in a locked room
grep restart * in the /var/log directory shows that the system restarted 
on Sunday 4 May at 4:02 - electrical storm?, and on 7 May at 19:15 - I 
did that to insert a UPS into the mix.