This is a URGENT MATTER to help me. My Computer's configuration is as follows Kobian Kob 815e Motherboard Intel Celeron II 633 Mhz nVidia GeForce FX 5200 Realtek RTL8139/810x Family Fast Ethernet NIC Primary Master - Seagate 20 GB HDD Primary Slave - Samsung 52X CDD I have two OS in my computer as follows C Drive - Windows 98SE D Drive - Windows XP Professional My SMPS is 250 Watts. I have 256 MB SDRAM. It is such as that 2 memory modules are inserted in the second (A1) and third (A2) DIMM slots. My problem started when I upgraded my computer with a new Sony DVD RW. setted as Secondary Master. The device worked finely for the day I installed it. The next day the computer gets restarted when I was working in Windows XP Professional. After the restart, when I try to enter Windows XP, it showed the following error in blue screen. (Error description) ——————————————————————— A problem has been detected and windows has been detected and windows has been shut down to prevent damage to your computer. The problem seems to be caused by the following file : ACPI.SYS An attempt was made to write to read only memory. Check to make sure any newly installed hardware or software is proprly installed. If this is a new installation, ask your hardware or software manufacturer for any windows updates you might need. Technical Information : STOP : 0x000000BE ACPI.SYS - Address F99F5ED8 base at F99E500, Datestamp 3b7d8550 —————————————————————- The error once read as follows —————————————————————— PAGE_FAULT_IN_NON_MEMORY_AREA ——————————————————————- I don't know want get wrong by the above message. When I referred for ACPI it reads Advanced Configuration Power Interface. Then I try to enter Windows 98 then it started showing the logo screen after that it doesn't show any error and get restarted. The second memory slot (A1) shows a speed of 127ns and the rest (A0 and A2) shows a speed 70ns (Referred by Everest Home Edition 1.51.195) then I inserted my SDRAMs in such a way that A0 and A2 are occupied with memory and the A1 is kept empty. (I checked the memory frequency it reads 133 MHz.) Then the system worked finely for two days. For this time I have writed 3 CDs and get readed by the DVD RW. I thought that the problem get solved. But after the 2 days, it get restarted. Help me. Now I disconnected the Secondary IDE connection with the DVD RW. So I can send this message to you. Now there is no restart. By I want my DVD RW also get working. So please please help me and Thanking you in advance. NB. If you want further details sent an e-mail to [removed] Hoping for a positive response at the earliest.