Continual crashing, slow starting and big problems!

Firstly, I apologise for my lack of technical knowledge and therefore the fact that this post may now make much sense. I have trwled lots of forums for help but nothing I have read has worked, so I am now starting my own thread.

The problem starts with the computer not booting, and then when it does, it takes an age. If I run check and repair, it tells me that it cannot repair the system.

In systen restore it says there are no recovery points.

When it does eventually boot, the toolbar is different, more basic looking. There is sometimes a bubble on the toolbar saying 'windows could not connect to the event notification service'.

Also on the toolbar, the speaker icon has an x through it and says something along the lines of its not running and other times the icon is not there at all.

All programs and functions are extremely slow, with widows explorer often restarting.

The problems still exist in safe mode - however we cannot get to safe mode from F8 for some reason and can only access it when the PC has switched itself off and we restart it and get the option.

I can schedule chkdsk for the next boot but when the system tries to run it, it just hangs.

sfc\scannow always stops at 26%

check and repair gives the message: unspecified changes to the system configuration might have caused the problem

repair action: system files check and repair.
result: failes. error code 0x45d

we have also come across

start up repair offline
6.1.7600.16385
unknown
39
autofailover
No root cause

We have removed Norton as it seems this can cause a problem. Windowes updates were disabled after previous problems but when we tried to run then (in case this was the cause) 21 out of 26 failed, but going back into the log the next day, it stated that we had not recently tried to install any updates

We have transferred photos etc onto external hard drive but is there anything we can do other than a fresh instal of windows 7?

We would be extremely grateful of any help.

When I can get into safe mode, all the same problems exist so I can do stuff, but it will hang internittently etc.

There is a lot of free space on the pc, it is literally used to photos, internet - no gaming etc, really only basic stuff.

Can I do the BSOD thing in normal mode or does it have to be in safe mode? It could take a good while to get it to re-boot again in safe mode, but will try if that's the only way.

Thanks for your help.

Ok the zip file should be on here but it doesn't have the perfmon HTML as when I tried perfmon/report it said 'cannot create file when that file already exists.'

Hopefully the zip file is attached, if not I will try again tomorrow!!

Thanks again