Ok I was woke up this morning by my better half saying that the computer was taking ages to log in and when it did it was popping up error messages. The main error message/problem was:
Failed to connect to a windows service
Windows could not connect to the System Event Notification Service service. This problem prevents limited users from logging on to the system. As an administrative user, you can review the System Event Log for details about why the service didn’t respond.”
So I booted up the laptop and began Googling for fixes. Searching for "failed to connect to a windows service" returns a ridiculous amount of results. I found multiple fixes (changing Remote Registry setting, manually setting network IP addres etc), none of which sorted my problem out 
Anyway I finally found a solution that worked (for me anyway).
Firstly we need to run the Command prompt with administrator privledges.
- Click Start then click on All Programs
- Now click on Accessories
- Right click on Command Prompt and select ‘Run as administrator‘.
or
- Click Start then click Computer (or open it from your desktop if thats where it is).
- Go to your C drive (or whatever drive you have Windows installed on)
- Open up the Windows folder
- Find and open the System32 folder.
- Find the file cmd (might be shows as cmd.exe).
- Right click on it and select ‘Run as administrator‘.
Once the command prompt window opens type ‘NETSH WINSOCK RESET CATALOG‘ and press the Enter/Return key.
It then says you have to reboot and after that my computer was working fine 
no more "failed to connect to a windows service"
Now I’m not saying this will work for you but it definately fixed my problem.
And please remember I am on Windows Vista not XP nor 2000.
<edit 15th March 2009>Been informed that this should also work on XP just wont need step 6</edit>
Thank you … thank you … thank you!
After trying lots of suggestions found on the web, THIS ONE WORKED!!!!!!!!!!!
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It worked! I thought I was going to have to repave Vista and Toshiba didn’t even ship a proper OS CD with the laptop. Several hours saved. Many thanks.
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You are a savior!! Aweswome Stuff…
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Thank you so much! I spent countless hours trying to fix that, using many tips from web, some of my own voodoo magic. With no results of course…
In fact there was one method that used to help, restoring some older system restore point. But guess what, this time I had no such points at all
One thing that you didnt write is that in fact its not just this service that failed to start (though its the one obviously visible once you finally go past ‘Welcome’ screen) Its many windows services that aren’t working (antivirus among them) I tried to disable or kick start them manually but nothing worked. What I was able to determine was that its one of windows core services, not anything I installed.
Things that may or may not help:
-I’ve seen this error on laptops that run out of battery
-This time though it seemed to be Spyware Terminator that blocked some network process (probably wireless drivers autoupdate)
I’m so happy I found this
Now i’m off to make many backups 
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Awsome ! You saved me !!!! thx a lot !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Why Microsoft don´t publish something like that ?!?!?!? What they r waiting for ???? Vista MF ….
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This really worked. Thank you for sharing this simple and effective fix.
This was the second time I had the problem with the home laptops. Last time I eventually had to re-install Windows Vista on one of them to make this go away.
I am glad I found this fix this time and saving several hours of aggravation.
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God bless thee!
)
It worked, and save me my study… Thank you, very very much!
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You deserve a medal!
It worked. Plain and simple.
What on earth caused this??
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Well for me it was installing an update to Windows Live Messenger that caused the problem.
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