Did you try resetting the hash on the distribution package?
I tried resetting the hashes but it did not work.One more addition to this:
1)When I try the http path it works perfectly..but for UNC path it is not working...
It looks like a permissions issue. Looking at your log:
Wed, 23 Apr 2008 15:53:22 ..\AdditionalFiles.cpp(205): (80070005): Failed to download file file://\\landesktest1\ldsoftwares\acrobat\adobe.exe : (80070005)
Wed, 23 Apr 2008 15:53:22 ..\AdditionalFiles.cpp(233): (80070005): Failed to download and hash all additional files
The error at the end of the first line indicates a permissions issue. Please take a look at this article to get this taken care of and let us know if it works!