An exact description of what happened and what is happening now, I tried to download a plug-in, and when I ran it, AVG detected a Trojan. My computer then went black, and then turned off. I turned it back on to find it could not start, and windows repair came up. After windows repair tried to fix the problem that was preventing the computer from starting, it told me it couldn't fix the problem and that sending the problem information off you Microsoft may help in the future. I have tried 'Dell safe data back up' and that failed, the exact problem name that comes up on the repair scan is ''Boot critical file c:\windows\system32\kdcom.dll is corrupt. Repair action: file repair. Result: Failed. Error code = 0x490

You may still be infected, run Microsoft’s System Sweeper, it’s beta but it works very well indeed. On a working machine download the 32-bit or 64-bit version, create a CD and run a full scan after booting from the CD, get it here https://connect.microsoft.com/systemsweeper

Hi James, Based on the error message, your system files got corrupted. Do you have a repair disc? Or you can use the Windows 7 installation disc to do a repair. Insert your disc, and boot from CD/DVD, choose to repair your computer. If you have a backup before your got effected by Trojan, try a system restore to that time. In addition, for more information and support on virus issues, I would also like to suggest that you call Microsoft PC Safety telephone number, 1-866-727-2338 (1-866-PCSAFETY). This service offers no-charge assistance for virus-related issues or questions. Also, you can check Microsoft Security and Privacy Web site at: http://www.microsoft.com/security/ Regards, Miya This posting is provided "AS IS" with no warranties, and confers no rights. | Please remember to click "Mark as Answer" on the post that helps you, and to click "Unmark as Answer" if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

you can login in safe mode and move the file kdcom.dll to any place as a backup and then take this file from anohter opearting system (windows 7) and copy to your PC in the path c:\windows\system32 restart and test it.