Thanks Vighnesh. I re-downloaded the file and this time it worked OK. However the issue was not due to corrupted download but to incorrect binaries. The zip file I originally downloaded contained esmcontenttpk.exe with time stamp 4/2/2013 1:09AM and the current file downloaded has time stamp of 4/2/2013 4:39AM. Also the md5 of the first one did not match expected value:
$ md5sum esmcontenttpk.exe
1c29c43bd002f728a330b94c18a7b3bc *esmcontenttpk.exe
$ cat esmcontenttpk.exe.md5
5fee7f3258fcc97b99baa272475dd4a4 *esmcontenttp
Newly downloaded has correct md5:
$ md5sum esmcontenttpk.exe
5fee7f3258fcc97b99baa272475dd4a4 *esmcontenttpk.exe
$ cat esmcontenttpk.exe.md5
5fee7f3258fcc97b99baa272475dd4a4 *esmcontenttpk.exe