Greetings, I have been having trouble installing 2 new 1.0 GB memory in slots 1 and 2, keeping existing 2 256 MB memory in slots 3 and 4 (starting with 4 256 MB boards and removing 2 256 MB boards). Initially I received a Stop 0x0000001A error with MEMORY MANAGEMENT, then subsquent boot showed 0x0000008E error. PC: Dell Dimension 5150 (everything original) (4) Dual In-Line Memory Module 256, 533, 32X64, 8, 240, 1RX16 (1) Hard Drive, 160G, S2, 7.2K, 8M Lead Free, WD-HAWK (1) Processor, 80547, Pentium 4 Prescott Dt, 630, SKT-T, Male Running: Windows XP Home 2002 Service Pack 3 Recently performed windows update Recently updated BIOS to A07 (from Dell site) History: PC was working, but seemed slow so I purchased (2) 1.0 GB Memory boards from Crucial. Popped them in slots 1 and 2, leaving old memory in place in slots 3 and 4. First attempt, was able to start windows (boot processs saw new memory, <F1> to continue) and verified memory by looking at "my computer" properties. Shortly thereafter, I experienced a crash with blue screen. Next Steps: On subsequent restart, windows peformed tests and corrective measures, but soon thereafter crashed with STOP: 0x0000008E. Note, I experienced a "crash window" of McAfee at start up, even though I didn't think I had any McAfee loaded or running (nothing listed in Add/Remove Programs, either). Used system restore to take PC back to prior state (a few days earlier), loaded old memory back in and everything seemed fine. I downloaded new BIOS (moving from A02 to A07), and created a new restore point. Loaded new memory and experienced blue screen stop before Windows log in appeared. MEMORY MANAGEMENT Stop: 0x0000001A. I replaced new memory with old and restored to prior point. Upon some additional research, I removed all McAfee software using their removal utility (MCPR.exe). Created new restore point. Everything seemed fine. Loaded new memory again. Upon some additional research on Windows site, I booted in Safe mode. Things seemed stable. Changed MSCONFIG settings for a Clean Boot with no SYSTEM.INI or WIN.INI, no Startup Items and only Microsoft Services. Things seemed stable (didn't do much, but did run Internet Explorer for a few minutes). Changed MSCONFIG settings for a Normal Boot and system crashed before Windows log in screen with Stop: 0x0000008E (0xc0000005, 0x8054B10D, 0xA7c44B50, 0x00000000). I am looking for the next step!! Thanks.