What is a Cabinet File?-A cabinet is a single file created to hold a number of compressed files.
What will you do if a .CAB file got corrupted?- You have to extract individual files from the cabinet files to replace missing or corrupted files.
How can you extract ?1] Press Win+R keys to launch Run menu.
2]Now type in:msconfig and click OK.
3]Click Expand Fille...
4]Name the file you want to extract in the File to restore box
5]Click Browse From tab to restore the file in the Restore from box.For example, the Windows XP .cab files are stored in the I386 folder present in XP CD.
6]Locate the folder where you want to Save file in.
7]Click Expand tab In the System Configuration Utility dialog box, click OK>Restart.
Ref:-Description and Explanation of a Cabinet Filehttp://support.microsoft.com/kb/q310435/