Finding problem with compact flash filesystem

I have a single board RHEL 5.8 computer that runs from a 4GB compact flash card instead of a HDD. This had been running for several weeks, with an application started and stopped for testing and being reboot several times - sometimes intentionally and sometimes inadvertently.

The card is now in a non-booting state. Here are the last lines visible on the screen

[   75.129972] end_request: I/O error, dev hdc sector 0
               mount: could not find filesystem '/dev/root'
               Setting up other filesystems.
               Setting up new root fs
               setuproot: moving /dev failed No such file or directory
               no fstab.sys, mounting internal defaults
               setuproot: error mounting /proc: No such file or directory
               setuproot: error mounting /sys: No such file or directory
               Switching to new root and running init.
               Unmounting old /dev
               Unmounting old /proc
               Unmounting old /sys
               switchroot: mount failed: No such file or directory
[   75.132340] Kernel panic - not syncing: attempting to kill init!
[   75.132399] Pid:1, comm: init not tainted 2.6.30.9 #1
[   75.132454] Call trace:
[   75.132517] [<c0122980>] ? panic+0x50/0x100
[   75.132572] [<c0125b48>] ? do_exit+0x678/0x740
[   75.132628] [<c0125c3b>] ? do_group_exit+0x2b/0x90
[   75.132684] [<c0125cad>] ? sys_exit_group+0xd/0x10
[   75.132741] [<c0102d31>] ? syscall_call+0x7/0x6

I would like to investigate what is the problem with this card - is it a faulty CF card, or has some code managed to scribble on the disc.

I have been able to boot using knoppix, but there is no filesystem recognised on the card and nothing is returned when I call fdisk -l.

I have tried to copy the disk using a card reader attached to a running Linux system with dd, but I get no medium error.

Is there any other way to investigate the problem with this card?

thanks