We have a Dell PC that has NT 4.0 installed on it. The machine would not boot after only three days of use so we installed it as a slave drive in another machine in order to recover the data files. In trying to "look" at the file system (it was in another NT box) we went to disk administrator and got a message indicating an error with the signature. We allowed it to write a new signature and the machine could then see the NTFS file system on the partition of the drive. We recovered all files and put them on another machine. After re-installing the drive in the original machine we tried to boot it and it worked fine. That was yesterday, today the problem has returned. What makes the signature get lost and is it an indication that the disk is failing?