Acer 8920g shuts down

Hello all, I recently purchased an Acer laptop and was thrilled to bits with the blu-ray side of it, however the pre-installed vista premium was one under my version (ultimate) so I decided to reformat and install it. On entering the bios I noticed that you had little leeway as it was very basic indeed, no cpu settings etc..

I removed the partitions too (including the backup one) as I would not have any use for vista premium and drivers can be downloaded from the acer site.
Once it had started the install it got to the point where it says 'expanding files' and suddenly died, the blue power light was still on indicating that the psu was live so I pressed it again and it sprang to life, this time it continued to load files and install right to the very desktop, a few seconds later it died, no warning, nothing, just shut off. So I hit the power button again and it loaded to the desktop, this time it lasted 5 minutes before cutting off. As I am relatively experienced in building computers I was wondering if the thermal sensor readings within the bios were screwed?

As I know of no way to get into the advanced bios (cannot find it anywhere) I don't know where to start. It is under warranty but I have heard horror stories of folks sending theirs in to get a bill for new fans etc.

Has anyone else had this problem with this laptop and if so what was the solution (if any).

many thanks