Found out my XP vm (virtualbox with ubuntu host) is not booting any longer. It could have been because I had to forcifully restart the laptop or not but the point is that if I try to start it, I will be told that "A disk error occurred; press CTRL-ALT-DEL to restart." If I reboot from the install CD in repair mode, I can mount the drive and run chkdsk. After doing its thing, chkdsk claimed the drive is ok. So, I looked at different directories in the drive at random and do not see anything out of ordinary (no files with corrupted names and so on). I even tried using fixmbr but that did not make the error go away. What else can I try?