ERROR: CANNOT UNITE READ-ONLY MEDIA AND INITIAL RAMDISK -

Hi im having some trouble booting on booting, ive tried safe mode but the above error always shows, is there something stupid i have done? i dont think ive got it horribly wrong - its in the boot process just after '/linuxrc: /bin/mount: I/O error'

i have have an IBM think Pad T30 if that has any effect on the error with 512mb ram - any ideas?