OK, I've found the problem. I did eventvwr.msc and found the errors at the time when i try to play a video (then my pc crashes).
I found these:
This is under the security tab,
IPSec Services: IPSec Services failed to get the complete list of network interfaces on the machine. This can be a potential security hazard to the machine since some of the network interfaces may not get the protection as desired by the applied IPSec filters. Please run IPSec monitor snap-in to further diagnose the problem.

This is under the system tab,
The NVIDIA NDIS IO Control Driver service failed to start due to the following error:
The system cannot find the file specified.

I also go this information when i went to the Microsoft help and support centre:
security error,
Product:Windows Operating SystemEvent ID:615Source:SecurityVersion:5.0Component:Security Event LogSymbolic Name:SE_AUDITID_IPSEC_POLICY_CHANGEDMessage:IPSec policy agent changed: %1
PolicySource: %2
%3

system error,
Product:Windows Operating SystemEvent ID:7000Source:Service Control ManagerVersion:5.0Symbolic Name:EVENT_SERVICE_START_FAILEDMessage:The %1 service failed to start due to the following error:
%2.

it also gives me an explanation and tells me to do the following,

ExplanationService Control Manager (SCM) could not start the specified service, probably because the service is not configured correctly.
User ActionDo one or all of the following:

• Review the error information displayed in the message.
• Verify that the service password has not expired.
• Verify that the service is in the correct location.
• Verify that the service is not infected with a virus.
• To display the WIN32_EXIT_CODE error that SCM encountered when trying to start the program, at the command prompt, type
  sc query service name
  The information displayed can help you troubleshoot possible causes for the error.

If the WIN32_EXIT_CODE is zero, then SCM did not attempt to start the service because the error was detected first.


Now i know what the problem is, could you possibly help me please?

Cheers,
FyawurX

:smiley: Hey Guys,

@Fyawurx, (love your screenname) Let's take these one at a time
Here are the instructions for loading and running the IPSec Service snap-in
http://support.microsoft.com/?kbid=324269

Next, disable your NVidia card in Device Manager, and reboot your computer, that will reinstall the drivers. It may be necessary to update them, or reinstall from a fresh download if they have become corrupted.

Now for this one
Click on Start, Run, type in CMD, hit Enter. Type in sc query IPSec hit Enter. Post the WIN32 Exit Code error back here.

Look forward to your reply,

TTFN

LGW

Do you maybe have or had "Nvidia DVD Decoder" installed on youre pc?

Have a look in youre device manager for "Nvidia NDIS IO Controller".
Set "hidden devices" to show by clicking on "view" and then "show hidden devices".

If you have it then right click on it and select "disable".

To ladygreenwitch,
On the IPSec Service snap-in thing i have done 1-4 on the Start IPSec Monitor. Is that all i need to do or do i need to do the whole thing, or the whole page?
I have had problems in the past from disabling my Nvida card. When i restarted my pc my moniter displayed, 'No input' or something like that and i had to reformat. Is it likely that it will happen if i do it now?

To joe5,
I don't have 'Nvidia NDIS IO Controller' but i do have 'nVidia WDM A/V Crossbar' and 'nVidia WDM Video Capture (Universal)'. The second one has a yellow circle with and exclamation mark in it on the icon.

Cheers,
FyawurX

Try to update it by rightclicking on it , or if that doesn't work , rightclick on it and select "disable" , reboot and see if that helps.

Can you download this app, and see if it can run all the files you cannot seem to play. This way we can work out other kinks if it is hardware related etc..(I use this program for all my audio and video files BTW)
http://www.snapfiles.com/download/dljetaudio.html

To joe5,
I disabled it and rebooted, it didn't automatically install new drivers and i still can't play videos.
ladygreenwitch said disable my nvidia driver but the two i mentioned to you are the only nvidia drivers i've got. I have installed the the driver from disc and from the download off the nvidia website; but they dont appear in device manager.

To waters,
I downloaded that app, tried to play a video on it and my pc froze. So i guess that means the problem is hardware related?

Cheers,
FyawurX