Windows 98 sometimes (often) rewrites a part of ACPI. in Windows 9x/ME Posted March 8 I write a small DOS utiilty for interfacing the ACPI tables. (here: ACPITOOL) In DOS it works OK but under Windows 98 it is not reliable. Sometimes it properly detect the ACPI interface 2.0 and everything is fine. But usualy it can't detect the ACPI. The debugging shows that the entrypoint RSDP (which is located in the first MB of RAM) is correct. It contains the pointer to the RSDT table which is mapped on the top of the installed RAM (to 512MB in my case). In DOS in this address is a valid RSDT table. But in Windows (in the same address) is often only some mess. Definitely a valid RSDT. What happens? Does it mean that Windows 98SE (or KernelEx or nVidia driver or ???) sometimes rewrite this memory area?