DGaines,
I'm sorry I forgot that it is trying to download the files via HTTP, not UNC so the file permissions do not apply in the same manner.
In this case you can test to make sure the file is accessible simply by entering the URL into a browser's address bar. http://10.3.100.55/ldlogon/LaunchProcessAsUser.exe
If it will download from that link without issue, then SDClient should be able to get it as well. If it is still failing you can enable XTrace logging on LDDWNLD and SDCLIENT to get more information.
How to enable XTrace Diagnostic logging in LANDesk Core and Clients
Let me know how it goes.
Bryce.