Hello,
ive got LAPTOP ACER ASPIRE 1500 (WITH AMd 64 ATHLON)
O.S. windows XP home edition(Italian)SP1

3 weeks ago it started restarting by itself after a blue screen w/c i was not able to write down.

Anyway i tried cleaning it with antivirus/Spyware scanners. But it keeps getting slower until it just blocked. i went to safe mode & it let work around it for awhile & afterwards it slowed down & blocked again & at the restart it said Operating system not found.

I gave it a 2 day rest & when i opened it this morning, ita had the message problem still not resolved start windows normally..but then it ran...

I checked the event viewer for Sept.2 problems and it had several errors& warnings like(ill try to translate in English)
DISK ID Event 51 \DEVICE\Harddisk0\D error in the device during paging operation & Error \DEVICE\IDE\IdePort0\didnt respond within the timeout period & \DEVICE\ACPIEC\embedded controller didnt respond in timeout period

Can you give me some advise..thanks in advance

Change this setting so that the next time it crashes you will see the error:

rt. click My Computer then click Properties then Advanced then Startup and Recovery Settings then unclick Automatically restart

The Operating system not found is indicative of a hardware & or BIOS issue.

Also run Check Disk:
start > run > cmd
in the new window type chkdsk/f
when prompted to run on boot choose Y & reboot
this will check for & fix any disk errors.

When your computer pages information to or from the disk, if a generic error occurs, it logs an Event ID 51event message. In a paging operation, the operating system either swaps a page of memory from memory to disk or retrieves a page of memory from disk to memory. It is part of the memory management of Microsoft Windows.

However, the computer may log this event message when it loads images from a storage device, reads and writes to locally mapped files or to any file (as long as it is buffered I/O). The computer does not log this event message when it performs non-buffered I/O. You can troubleshoot an Event ID 51 event message the same way as you troubleshoot Event ID 9 or 11 event messages.

For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
154690 (http://support.microsoft.com/kb/154690/) How to troubleshoot event ID 9, event ID 11, and event ID 15 error messages
259237 (http://support.microsoft.com/kb/259237/) Troubleshooting event ID 9, 11, and 15 on Cluster Servers
http://support.microsoft.com/default...b;en-us;244780