Apologies if I'm posting in the wrong forum but I'm new, I'm a computer novice, it's late and my laptop is scrambling my brain

A couple of weeks ago my ASUS F5 laptop (running windows Vista Home Premium SP2) started playing up. The screen would freeze and the laptop stopped responding, the only way to go was hitting the rest button (ctrl Alt Del doesnt work). This began happening more frequently as the days went on. I found it was usually when I was accessing the internet or had more than 1 program running at a time. Opening Firefox and Thunderbird together was a recipe for disaster, anything with flash or multiple images was a definite no go. I checked windows task manager and noticed that my physical memory (usually at about 40%) was running at 95-100% immediately before the freezing.
I used the windows memory checker to make sure my memory was ok, all is fine apparently. I've got 2GB RAM and a partitioned hard drive with 106GB free on the D Drive and 78/116GB free on the C drive. I've dismantled the laptop and given it a blinking good clean so it's not overheating. I've tried using different browsers; makes no difference, I just get "not responding" every 5 minutes and a complete freeze randomly, besides of which the actual windows bits are lagging like crazy too (5 minutes to open the start menu?)
I scanned for viruses (used AVG and then Avast) neither found anything. I also ran malwarebytes and hijackthis, also both clean.
In a last ditch attempt to restore the dratted thing to a usable condition I backed up my files and started over.
This resulted in a super speedy and very happy laptop. Then the windows updates started coming. I installed the lot all in one hit every time they popped up, all good. After a day or 2 I put my files and programs back on. Lovely. Then I got a set of "important" updates, one of which was the .NET framework 3.5 upgrade. I installed them and my laptop's back to square 1

So I deleted everything again and started over; this time I installed the updates one at a time (I've been here 10 days!) all good until the .Net framework thing went back on. I've tried uninstalling it, no joy, I've tried a system restore, not working and I'm not loving the thought of having to reset the thing for a third time.
Basically I have to have this .NET framework 3.5 thing for the ATI CCC to work. If I dont my graphics card drivers wont update and nothing works anyway

Help!
Now it's doing this:
Now it's doing this:
Problem signature:
Problem Event Name: BlueScreen
OS Version: 6.0.6002.2.2.0.768.3
Locale ID: 2057
Additional information about the problem:
BCCode: a
BCP1: 00001014
BCP2: 00000002
BCP3: 00000000
BCP4: 826717C0
OS Version: 6_0_6002
Service Pack: 2_0
Product: 768_1
Files that help describe the problem:
C:\Windows\Minidump\Mini072912-01.dmp
C:\Users\Gael\AppData\Local\Temp\WER-184718-0.sysdata.xml
C:\Users\Gael\AppData\Local\Temp\WER2C70.tmp.version.txt
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Edited by wickedpixie, 29 July 2012 - 05:55 AM.