Long time to START booting, not long time to boot

My netbook takes a very long time to START booting, not to boot, but to START booting, i.e a long time before it even starts to load windows.

It is an Acer Aspire 1 D257, Intel Atom N570, 2gb ram, 320GB hdd, Win 7 professional SP1

This is not a windows problem, windows boots very quickly. I keep it running well, I run scandisk often and clean the registry. It has ample space for virtual memory, it runs very quickly. Windows is very stable.

But the laptop won't START booting i.e. it takes a long time for the manufacturers logo, ACER, to even appear, a long time before the laptop even accesses the HDD. The fan comes on for a 10 seconds then nothing happens.

Once it starts loading windows it boots very quick.

Sometimes, after it has taken a long time to get booting, it crashes as soon as it starts loading windows then reboots, as if the power had suddenly been disconnected then reconnected (exactly like a reset button had been pressed).

I have to restart it, up to 10 times before it will get going (this has got progressively first). Or if I just leave it on, after 5 minutes or so (never the same length of time) it just starts booting by itself.

Once windows is loaded it NEVER crashes so it can't be a memory or HDD controller problem.

I am running it with a replacement PSU, one that is specifically designed to work with different types of laptops with different power requirements (it could deliver more power than my netbook needs)

The delay in starting happens both on battery, without PSU connected, and with the PSU connected with the battery too. The battery is not damaged, it charges fully and lasts the correct length of time.

Sometimes if I disconnect the power supply when windows is running, the computer crashes instantly, even when the battery is fully charged and connected.
Or else the screen gets corrupted and the picture disappears leaving just a mass of vibrating colors, like a speed smeared photograph. Sometimes it boots into this same unintelligible screen.
This screen never appears when the computer is running normally whether it is on battery or with the PSU.

If I have been using the laptop for at least 10 minutes then I can reboot it without the delay in start up occurring. If I leave it for an hour then the problem is back.

I am using the laptop in a hot country but the problem occurs in the heat, in A/C rooms, in high humidity and in dry conditions. The problem occurs if the laptop is right side up or upside down. The HDD is connected properly, the memory is seated correctly.

I would like to know how to overcome this problem.

I have the latest BIOS and the problem occurs no matter what settings I choose there, including those for QUIET BOOT, NETORK BOOT, F12 BOOT MENU, D2D RECOVERY. The boot device is set to the HDD, there is no password on boot. The BIOS version is v1.1.15, Intel v2036. I have not left any card in the card reader.

In anticipation of the guy who will advise me to leave it on all the time, that's not possible, I am traveling (I never use the laptop when I am in transport, only stationary).