Years ago I built my first system with Abit IP35pro, Western Digital SATA HD, Windows Vista, etc. The build went without a hitch and was great for years. Last night I decided to vaccuum the inside of dust. Did it before without event but now system hangs on boot. Did it with power off but plug in, thinking the ground connection would be good. It hangs after ACPI Controller irq9 and wants to boot from CD. I was afraid I perhaps zapped my bios??? After looking for anything loose and verifying power to my hd and trying a different sata cable, I put in my original Windows installation DVD. Message changed to press enter to boot from cd/dvd and a few seconds later it booted from my actual Hard Drive since all my files and desktop showed up. No reinstallation took place. Seemed like system saw the DVD but then was directed to boot as normal. Trying it again without the Windows DVD repeats the problem. I could only boot with the DVD in. Was too late to continue last night. Going to work now. Any ideas?? I'll check back after work.. Thanks.