You need to find the specific process that's taking all (there are lot of
sub-processes tied to the 'System' process) the CPU resources and taking
down/crashing your PC.
To do this try Process Explorer:
http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx
Once you have Process Explorer installed and running:
In the taskbar select View and check 'Show Process Tree' and 'Show Lower
Pane' options.
(This will provide some of the detailed info you need)
Next click on the CPU column to sort processes by %CPU usage.
Then click on and expand the 'System' and 'Explorer' process to expand and
identify the specific sub-process that's using most or all the resources.
Click on any process or sub-process to highlighted it,
right click and from the options listed select: Search Online.
This should display what out there on the web about that process.
Note: some entries like Explorer, System process (as explained above)
and svchost entries may need to be expanded to show
the detail (sub processes), in this case click on the + located to the left
of the entry.
If you need to stop an application (Process) from loading:
Try Autoruns from the MS Windows SysInternals site:
http://technet.microsoft.com/en-us/sysinternals/bb963902.aspx
AutoRuns will show/list all apps/etc. that load/run when you first boot ...
(the 'Boot Execute' tab),
when you logon (the 'Logon' tab) and other programs that load
(grouped by labeled tabs) for easy viewing.
It also provides the ability to selectively allows you to stop
(use with care) any program that you don't want to load.
You can undo any changes you have made.
Note: To get additional details on an item in the list you can't
readily identify you may need to highlight the item (right click) and use
the 'Search Online' option to get the details,
especially useful for the more obscure items in the list.
There is also a change in the latest version's (v9.39) menu 'Options':
"Autoruns changes the Hide Microsoft Entries to only hide Windows entries"