Hi Joe,
I suppose you are using a Dell PC.
Error Code: 2000-0142 means that the hard drive has gone bad and requires a replacement. As you are able to boot into windows, I recommend you to backup the data on an external hard drive. If you are still under warranty then you can try contacting Dell support and they will dispatch out another hard drive.
To test the hard disk, please follow these methods.
Method 1: You may run the hard drive self-test from BIOS and check:
http://windows.microsoft.com/en-US/windows7/BIOS-frequently-asked-questions
Note: Modifying BIOS/complementary metal oxide semiconductor (CMOS) settings incorrectly can cause serious problems that may prevent your computer from booting properly. Microsoft cannot guarantee that any problems resulting from the configuring of BIOS/CMOS settings can be solved. Modifications of the settings are at your own risk.
Dell PC diagnostic
http://www.dell.com/support/Diagnostics/in/en/indhs1/
Method 2: You can also run a check disk.
Check a drive for errorshttp://windows.microsoft.com/en-US/windows7/Check-a-drive-for-errors
Note: While performing disk check on the hard drive if any bad sectors are found on the hard drive, the check tries to repair that sector. Any data available on that might be lost.
I would also suggest you to post your query in the Dell Support forum.
http://en.community.dell.com/support-forums/
http://www.dell.com/support/home/us/en/indhs1?c=in&s=dhs&cs=indhs1&l=en
Follow these steps and let us know if it helps. Also, please provide us more information on the issue you are facing.