This is a very strange problem. Can't say I've seen it before.
Lets just get the basics out the way first.
Please can you download and install Everest from HERE
Once its installed (leave all of the options just keep pressing next) double click on the shortcut.
Then once its running:
1: In left pane expand Computer folder
2: Click once on Summary
3: In upper menu, go Report
4: And then to Quick Report-Summary
5: Save it in text file, and paste it in your next postDon't include anything under the line "DEBUG- PCI"
The attached picture can be used for reference
Also did you not do anything in the time it working to not working? Eg didn't change it or move it in anyway?
It could be a bad board but might not be.
One more thing is the disk drive shown in the BIOS?
When you turn on the PC look for [b]Press F... to start Setup[b] ... being the number of the F key eg F2. Its normally something like F2 or Delete.
Then go to the [b]Boot[b] tab
Click on CD-ROM drive and see if its listed.
If its not listed let me know. Also if you cannot find for example the Boot tab then let me know the BIOS make of your mobo for example in a black screen when you boot up it might say Phoenix Award BIOS doe example.
Any issues let me know.