I was able to 'fix' this issue by replacing the hard disk. While I was doing some heavy I/O on the harddisk, the DMA timeout occured and the filesystem crashed heavily! I decided to replace the harddisk (7200 rpm instead of 4800) and I didn't observe the issue anymore.
-- DMA timeouts on UDMA harddisks https://launchpad.net/bugs/25975 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs