My imac has been running without problems under OS X Snow Leopard and bootcamp running Windows XP for a long time. I had received a Sony MP3 player and wanted to install the software on my computer. At the time I had a CD in my drive slot because I was getting ready to install some brother's software for a printer I wanted to use. I restarted my imac under bootcamp and started installing the Sony software in Windows XP. I was having problems with the install and decided to restart XP to see if that would help. It's been several days since this originally happened so I'm not of sure of any more specifics at this point other than I've had to use windows machines for a long time and know that basically when in doubt "restart".
When my imac was restarting I heard everything spinning up, the white light came on, but I heard no chime, a blue screen came up for about 15 to 30 sec. and then it went to a black screen with DOS characters giving the following message:
Windows could not start because the following file is missing or corrupt: <Windows root>\system32\hal.dll. Please re-install a copy of the above file.
I do have a copy of Windows XP, but my first problem was that I still had a CD in the slot and it would not eject. I tried every keyboard combination I could find including: eject button, F12 and holding down the mouse button at start-up and nothing worked. I also tried every other start-up keyboard combination I could find at Apple Support jut to see if I could get my imac to start up under OS X . I finally went on youtube to find out how to remove the CD. I ended up opening up my imac and taking off the cover of the CD drive to remove the disk. After putting everything back together I put in my Windows CD and tried restarting again. The exact same thing happened and I ended up at the DOS screen. Then I thought maybe my keyboard wasn't working so I replaced it with a new one. Same result. I also thought to plug both of my apple keyboards into my windows 8 laptop (hate it!) to see if they worked there at all. They both did so I'm sure the keyboards are not the problem.
At this point, since I do now have a windows 8 laptop (hate it!) there is no remaining reason for me to keep a bootcamp partition on my hard drive. My question is where do I go from here? I have a current time machine back-up on an external hard drive and I have my install CD for OS X Snow Leopard. How do I get my imac back up and running? Thanks.