I have installed Backtrack5 on hdd with dual boot Vista on my Acer Aspire 5315.
Vista works fine but when I spend 10 - 20 minutes on backtrack, the laptop just shuts off. mostly when I ran an application like wireshark or ettercap-ng, but not always the case.So I don't think its a software problem. As 90% of the time it is random shutdown.
I have a faulty battery, which only lasts 5 min, but I am always on AC power supply. When Backtrack starts it gives me a message at the bottom right saying that my battery is faulting and only has 30% power, yet I am on AC power. I have removed the battery and only used AC but when I boot BT5 it just stays on a logo screen and no command to log in. So what could I do next. Please remember that I am a newbie.

If it only happens when you start programs that use your wireless card then there may be a driver issue. There's also the possibility of overheating causing the shutdowns, especially if it's at the same time after bootup. To rule that out, boot up and then do nothing (especially not your wireless programs) and see if it stays up longer. Also, Google your wireless card (use lspci to get it) and Backtrack to see if there are any known issues.

After Googleing I found out that my Acer overhears because it needs a software to start the fan (epower under Vista) but the only way to make the fan work under ubuntu is to install Acer_fancontrol, which I have installed but now btw freezes on start up.
I'm stuck