Problem Signature Blue Screen

Hi all,

I am using an ASUS laptop that has the following configuration:

Asus Notebook C90 Intel C2D E6600, 2.4GHz/3gig RAM/160 Gig Hard-drive/DVDRW/15.4"\WXGA\Vista Ultimate.

This issue I am having is a blue screen appears at random intervals. The information that appears can be seen below: Can anybody find a solution to this issue it is proving to be very frustrating.

Problem signature:
Problem Event Name: BlueScreen
OS Version: 6.0.6000.2.0.0.256.1
Locale ID: 3081

Additional information about the problem:
BCCode: a
BCP1: 8C4524F4
BCP2: 00000002
BCP3: 00000001
BCP4: 81CE9874
OS Version: 6_0_6000
Service Pack: 0_0
Product: 256_1

Files that help describe the problem:
C:\Windows\Minidump\Mini092608-01.dmp
C:\Users\melanie.MACROPLAN\AppData\Local\Temp\WER-402154-0.sysdata.xml
C:\Users\melanie.MACROPLAN\AppData\Local\Temp\WER5762.tmp.version.txt

thanks