I thought it to be a hardware issue, I reinstalled the entire CD drive. Then tried to boot, it boots up properly. Then I tried to install to hraddrive(chose "use entire harddisk" option), no problem installation went fine. Then I went into storage media, there I noticed that entire only 150B out of 250GB space is being recognized rest 100 GB is missing. what could be the problem? is there any way to get it back?