I'm losing it. I have had XP working on this box for months. All the sudden I rebooted the other day and I got the "Unmountable boot volume" error. Ok... so what, I wanted to reinstall fresh anyway and I have Ghost images as backups, right? WRONG! Here's my oddysey: I got these errors while trying to install from XP CD: could not load setupdd.sys (went away when on different IDE port) "your bios is not acpi compliant" DUH, it was yesterday. (have since flashed BIOS to same bios/latest to be sure) then when I moved the HDD to another IDE port it would get to the copying files where I got these errors: "could not load blablabla.bla" try again... it would be a different file every time. I thought I had a bad CD, so I used a friend's and same story. I have several partitions so I backed up everything, did a low-level format of my HDD, recreated the partitions, completely dida 4 hour HDD check with Western Digital's disk doctor program which said drive was 100% working. I tried installing again and get same errors.... ok, so it's not HDD, not the CD, maybe it's the CD-ROM drive. I use another and I get same thing. Maybe it's XP... I try to install WIN98 and it installs perfectly.... BUT, now my box gets a VXD VCACHE blue death screen every 5 minutes or so. It usually happens when I try to transfer large files or do web stuff. (outlook, explorer) I even put the WINXP disk onto one of my partitions and tried to install but I got the blue screen VXD VCACHE problem. I set all BIOS to optimized, then fail-safe, set all ram timings low, took out ram one by one, and I still can't get XP to install or 98 to work without tons of errors. I'm not overclocked, and this thing worked perfectly last week. I did not do anything to my box lately either, no lightning, static, anything. I will be so appreciative if anyone can give some advice... anything. I can usually figure this all out myself. I have not tried to get another HDD yet (seems to work fine and tests fine), but that's my next course of action. Thanks for any feedback. God bless you if you read all this, you are a good man. ps- i should tell you my ram has been flaky.. it only reads as 392 when it should be 512. also, i was using ntfs with XP.