My computer runs with a Samsung 512MB RAM memory module-DDR 3200 400mhz. Ordered a Crucial with same specs and installed in second slot. Boot process hangs when Windows starts to load(XP Pro). Removed both modules and started with Crucial installed only. Everything OK. Then installed the Samsung in second slot and it was not recognized but everything loaded fine. Mainboard is VIA P4PB 400-FL and processor is a P4 2.4 Ghz. Hope this is enough info and someone can help. Thanks a bunch.