After the computer starts up, it can complete self-check, but it cannot go into the system (xp sp3). Moreover, the infinite loop restart solution has a small problem on the computer today, resulting in the failure to start the computer, and the BIOS can go in, self-check can be completed, but the system cannot be entered. Even the security mode cannot be used. It took an afternoon to finally get the computer ready. Next, let's talk about my solution: 1. First, we need to enter the security mode, because I have ruled out the reason for loose memory, and I can't do anything else if other hardware is broken, I think that if the hardware is broken, we should not be able to connect to the BIOS, rather than just the last step. The possible cause may be that the system is poisoned. Restart your computer -- press F8 -- use the up and down arrow keys to select "directory service recovery mode" -- wait for it to automatically complete 5 steps. Then a dialog box is displayed, and select "yes ", enter security mode. Then start anti-virus software to scan for anti-virus... My computer has scanned two viruses, but I don't know what the virus is. It's almost done here (but I tried to restart it when I didn't arrive here, But I did step 1 ). 2. After that, I disabled the self-check function. For details, click Start> Run. In the run dialog box, enter regedit to open the Registry Editor, select the "HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Control \ Session Manager" subkey, find the "BootExecute" key value in the window on the right, and clear the value, press F5 to refresh the registry. This is now Europe. The computer is successfully started and runs normally.