Although ext4 is the default filesystem type in newer ubuntu versions, ext4 was not a stable file system when intrepid was released. There are unstable packages under intrepid but reaslistically ext4 is not supported on 810 intrepid. I'm also not sure what, if any, glue that lmce may require to recognize it. There are testing packages in intrepid that you could enable to try but I would be leary of trusting my data to it. I don't believe it's possible to convert an ext4 filesystem to ext3 so your primary option is to copy everything off the drive, reformat it ext3 and copy all you files back on.