Sony, if they don't support it means that if it doesn't work, go back to what worked. Install Vista again and if it hangs up there then you have a machine in need of repair. The hard drive going missing could be a sign.

What sign? That the laptop is not getting its yearly cleaning. Example at http://reviews.cnet.com/4520-3121_7-6679060-1.html

Many didn't know we need to clean these things.
Bob