I've also seen firewalls cause this behavior...if svchost is trying to make a network share available and you have a firewall that's not setup to allow the server the machine thinks it should get the resource from you'll see svchost chewing up cpu time and horrid system response...this is only if there is a network connection available, try disabling your network connection if you're running a firewall and see if you still have problems.
Disable fast user switching from MS:
http://support.microsoft.com/?kbid=279765- Log on to the computer as an administrator.
- Click Start, click Control Panel, and then click User Accounts.
- Click Change the way users log on or off.
- If it is not already selected, click to select the Use the Welcome screen check box.
NOTE: The Use Fast User Switching check box is unavailable until you click to select the Use the Welcome screen check box.
- Click to select the Use Fast User Switching check box, and then click Apply Options. Quit the User Accounts tool.
Ok...and I'll add a note for those of you in a domain schematic or who switch from the MSGINA or use Netware and fast.exe is still enabled:
go to
Start-->Run-->msconfig head to the
startup tab and uncheck "fast.exe" if it's checked or remove XP Powertoys if you're not using it.
About the "system" taking up 100%, check out this app...it breaks down system rather nicely:
http://www.sysinternals.com/ntw2k/fr.../procexp.shtml
You can find processes that carry out their sloppy process handling under the name "system" and get an idea of what is chewing up processes and uninstall it if you don't need it.
For the reboots I'd be looking into a BIOS update as well as taking stock of any new devices/software installed...for software specifically VPN clients or apps that also install a device driver. I've seen ACPI cause some stuff random reboots but that would have been happening from the start so overheating would be a good guess. I had a situation with a Dell laptop where it kept shutting down for no reason and found out that the BIOS had been originally programmed for Pentium III specs which couldn't handle as much heat as the Pentium IV machines so...basically it was shutting down because it
thought it was too hot but really was just not programmed with the correct specs for the new hardware...so, check out the BIOS if you didn't build that machine yourself.