Must disable driver signing after windows update in vista

I have a brand new dell laptop which has had no other programs installed on
it except vista business. I had put spybot and comodod firewall on but had to
take them off as they seemed to prevent windows from installing updates. So
i've got a blank laptop again. I then proceeded to update vista (14 Updates
mostly vista security ones with a couple for the vista mail programe and 2
for .net. Also one Cumulative update for IE 7 which I cannot install
otherwise windows will not boot up.) No other program updates !!

Now the issue is, I have installed all but the IE 7 one and created a
restore point there. Now every now and then when using the laptop for
browsing it just dies with lines on the BSOD (No error visable - like smudges
wrting) and I can reboot but windows will not boot up unless I hit F8 and
disable driver signing enforcement or go back to the manual resotre point I
created which is the same point in the system I should be at as I have not
installed anything else and have disabled windows update. Sometimes however,
the laptop will be fine and I can reboot it many times. Then the next morning
I turn it on and the same thing happens. Gets to the loading windows green
bar and then all i get is a black screen with the mouse and no further. I
either have to restore the pc back to the same damn point it is already at
and wait for it to fail again or disable driver signing on boot up.

Can anyone at MS explain what the smeg is going on here and why / which MS
updates coule be causing this. The 13 I installed are listed below:

Security Update for Windows Vista (KB931213)
Security Update for Windows Vista (KB935807).
Windows Malicious Software Removal Tool - July 2007 (KB890830)
Update for Windows Mail Junk E-mail Filter [July 2007] (KB905866)
Security Update for Microsoft .NET Framework, Version 2.0 (KB929916)
Update for .NET Framework 3.0: x86 (KB932471)
Windows Malicious Software Removal Tool - July 2007 (KB890830)
Update for Windows Vista (KB936825)
Update for Windows Vista (KB931836)
Update for Windows Vista (KB933928)
Update for Windows Vista (KB935280)
Update for Windows Vista (KB937077)
Cumulative Security Update for Windows Mail for Windows Vista (KB929123)
Definition Update for Windows Defender - KB915597 (Definition 1.20.2824.2)

Installing this gives the boot problem straight away on reboot so my manual
restore point is at this stage:

Cumulative Security Update for Internet Explorer 7 in Windows Vista (KB933566)

Anybody got a clue as to why MS Updates would need driver signing disabled?
Also why does windows update tool not load when driver signing is disabled?

Please help i'm going nuts with this. Maybe time to consider Linux again....