User Feedback :: /dev/sda1 is not a valid block device
I encountered a similar problem with a zip drive.
It did'nt accept /dev/sda1
but when I tried /dev/sda all became OK.
I have no explanation.
Try it, it's very quick.
In the latest DSL distro 5.xx you are unable to mount certain/all sub memsticks with Brand NEW pc's. I thought it had something to with USB 2.0 support but disabling it at boottime had no succes.
I solved the problem by upgrading to kernel 2.4.24-xfs
The full knoppix V3.3 with 2.4.22-xfs kernel does not have the "not valid block device" error. There must be a bug somewhere, I guess it's the /kernel/drivers/usb/usbcore.o module.
I advice to just upgrade all modules + kernel but that's more then just a little afternoon of work. You could also downgrade your motherboard
Succes, Krezip. 
What you should get when doing "modprobe usb-storage" ;
**** DMESG OUTPUT : ****
B device 00:07.2-1, assigned address 2
usb.c: USB device 2 (vend/prod 0xed1/0x6620) is not claimed by any active driver .
Initializing USB Mass Storage driver...
usb.c: registered new driver usb-storage
scsi3 : SCSI emulation for USB Mass Storage devices
Vendor: Model: Rev:
Type: Direct-Access ANSI SCSI revision: 02
Attached scsi removable disk sdb at scsi3, channel 0, id 0, lun 0
SCSI device sdb: 2047808 512-byte hdwr sectors (1048 MB)
sdb: Write Protect is off
sdb: sdb1
WARNING: USB Mass Storage data integrity not assured
USB Mass Storage device found at 2
USB Mass Storage support registered
**** EOF DMESG ****
When you do "mount /dev/sdb1 /mnt/usb" it'll work fine but not with DSL V5xx release on Brand New motherboards. On older system it's no problem.
I think we need a new DSL distribution. 
Try using simple readers like the $19 Dazzle or the Sandisks. Don't hook up the digital cameras, that complicates matters. I've been greatly successful mounting USB devices of all kinds when I just make matters as simple as possible. Remember, many CompactFlash cards have IDE controllers built in (at least according to a tech I know who has designed such things for 20 years). So choose the simplest, least-intrusive interface possible. I've mounted memory sticks, SD cards, external hard drives, Zip discs (use sdb4, an old secret recipe because Zip comes out at #4, don't ask me why), all kinds of things. But never a digital camera.
Hope this helps...
RobertVan:blues:
original here.