This is a story regarding 3 laptops of different brand and models.

On separate occassions, I configured each of these Windows 7 / Vista computers with the necessary configuration and applications (which are supposedly the same actually), e.g. join office domain, same windows updates, microft office etc.

These machinese were configure in our office in Singapore, and then they were taken to India for use.

Someday in India, when booting up the laptop, all went fine except when it reach the log in screen, it was no longer possible to login with domain credentials. Logging into the laptop local admin account will lead to discover that the machine has returned to "OS-only state". All the configurations and applications were gone. The actual user profiles are still in the C: drive so files can still be retrieved, but under Control Panel > Uninstall Programs it is evident that at least the registry is corrupted.

The above scenario happen to the first 2 laptops. For the third, the system reports "Operating System Not Found" on boot up.

I cannot think of any reason except to suspect a power fluctuation issue. Question is, will a power issue create this behaviour? What else can cause this issue?