I have a 1999 Compaq Presario 1278 notebook cpu. I stoped using it about two years ago. I don't remember what I was trying to do, but I remember inserting a floppy, then when ever I tried to start up the cpu the screen turned black and I got the message "Invalid System Disk. Replace disk then press any key." I recently attempted to start the cpu and got the same message. I found my way into the BIOS system and change some configurations around and was able to get a black screen saying "Operating System not found." I reset the defaults in the BIOS Setup Utility only to be returned to the original message, "Invalid System Disk. Replace disk then press any key." I contacted HP tech support through chat online and after going through all of their checks they informed me that I would need to purchase a retail version of an operating system such as Windows XP. Ok so I bought Windows XP, inserted it into my notebook, nothing changed. I chatted with HP tech support again who informed me now that it was a hard drive malfunction and that I would need to purchase a new hard drive. So I did. I have inserted the new hard drive correctly. The notebook now starts up and goes to a black screen and shows "Operating System Not Found." I contacted HP tech support again, this time the tech asked me to tell him if the light for the cd-rom drive was on. I explained to him that this model doesn't have a led indicator for the cd-rom. The tech then informed me that because Windows 98 was orginally on the notebook I will not be able to put Windows XP on the notebook and because the notebook is not reading my cd's (neither Windos XP nor the Emergency Restore Disk) I need to replace the cd-rom drive. ant this rate I will have spent as much money as buying a new laptop. Can someone aid me? It seems HP tech support is only suggesting that I spend money on something to get me off of the telephone or end my chat session without really trouble shooting the problem.