Saludos, si tenéis Windows XP y se os reinicie con bastante frecuencia el PC tal vez sea debido al S.O. A mi me ocurría y lo solucioné con lo siguiente:
Computer Restarts Unexpectedly When You Browse the Internet
The information in this article applies to:
Microsoft Windows XP Home Edition
Microsoft Windows XP Professional
This article was previously published under Q316416
While you browse the Internet, your computer may restart unexpectedly.
This behavior can occur if both of the following conditions are true:
A broadband cable modem or an asymmetric digital subscriber line (ADSL) modem is installed on your system, and the modem is using drivers that cause a fatal system (STOP) error.
NOTE: Depending on your system configuration, the resulting blue-screen error message may not be displayed long enough for you to record the error information.
The Automatically restart check box is selected under System failure in the Startup and Recovery dialog box (under System Properties).
To resolve this issue, follow these steps:
Start Windows XP in Safe mode, and then configure Windows to not automatically restart when a STOP error occurs. To do this, follow these steps:
Restart the computer. When the POST process completes, press F8.
On the Windows Advanced Options menu that appears, use the ARROW keys to select Safe Mode, and then press ENTER.
Select the operating system to start, and then press ENTER.
Log on to the computer as Administrator, and then click Yes in the Windows is running in safe mode dialog box that appears.
NOTE: When the computer is running in Safe mode, your display settings may be set to a lower resolution than you expect.
Click Start, and then click Control Panel.
Click Switch to Classic View if Control Panel is not already in Classic View.
Double-click System, click the Advanced tab, and then under Startup and Recovery, click Settings.
Under System failure, click to clear the Automatically restart check box.
Click OK twice.
Close Control Panel, and then restart Windows normally.
Attempt to browse the Internet normally. If you receive a STOP error message, attempt to determine the source of the problem by using the error message information that is displayed.For additional information about how to do this, click the article number below to view the article in the Microsoft Knowledge Base:
265879 How to Debug "Stop 0xC2" or "Stop 0x000000C2" Error Messages
Attempt to obtain updated drivers for your ADSL or cable modem.For information about how to contact computer hardware manufacturers, click the appropriate article number in the following list to view the article in the Microsoft Knowledge Base:
65416 Hardware and Software Third-Party Vendor Contact List, A-K
60781 Hardware and Software Third-Party Vendor Contact List, L-P
60782 Hardware and Software Third-Party Vendor Contact List, Q-Z
Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.