Open Explorer and go to the Windows\Inf folder. Locate the srchasst.inf file. Right click it and select Install. You'll need your XP CD or the files from the I386 folder. (This fix will require you to have your Win XP CD).
The Windows\Inf folder is a hidden folder. You can adjust your Explorer Folder Options (View tab) to Show hidden files and folders. You can also click Start, Run and enter %SystemRoot%\Inf to open directly to the Inf folder.