AOA 150 random freezes/general problems

Hello,

Specs:
Refurbished AOA 150
Windows XP SP3
120gb hd
1gb (now 1.5 gb) RAM
1.6ghz atom
8.9 in screen

I've had my netbook for about three months now and up until this past weekend it has been the best laptop. This past Saturday while using the laptop it froze and a loud beep came from it. I had to hold down the power button to force it to shut off. It will do this every now and then but more frequently tasks will stop responding to the mouse/keyboard/task manager then everything will stop. It is almost as if the explorer process is freezing becuase when I try to right click, the menu will stay half way faded after clicking away and when trying to get into the start menu the task bar will freeze (clock, start button, tasks). I cannot hibernate/sleep, it will freeze at the screen "Preparing to hibernate" and every now and then it will hang when trying to shutdown.

This happens, though less frequently, in safe mode with networking but I have not been able to recreate in standard safe mode. In standard safe mode I was able to backup all my files (about 40gb) overnight and it was fine the next morning.

Below are the steps I have taken in trouble shooting.

Full chkdsk at book reported no problems
Windows Memory Diagnostic reported no problems after 45 passes (about 2 hours)
Flashed BIOS to latest version at Acer website
Ran eRecovery
Purchased a 1gb stick of ram and replaced 512mb that came with this laptop
Ran eRecovery again.

My initial thought was bad ram but the memory test and the new stick have proven this not to be the case. I don't think the hd is bad because I was able to copy a lot of files and do the eRecovery twice without error. So, I guess this narrows it down to a MB/CPU issue or a network issue.

Has anyone had any experience with this type of problem? Please let me know if I am unclear about something.

Thank you for your time and responses.

 

I've removed the wireless card and the problem still persists, so my only assumption is that this is related to the motherboard.

I don't think that temperature is the problem, I am using AA1 fan control and it idles at 48C without the wireless cad and 53C with it.