network share security - mscorlib

I have used the caspol tool and tried to set security for the network share
but still getting errors containing:
"System.Security.Permissions.UIPermission mscorlib" and
"System.InvalidOperationException".
The program is a small exe created with VB 2005 - runs fine in the IDE, runs
fine on another Win XP pro machine (with the exe on a network share on Win
2003). The PC it gives the errors on is my development PC - again, only when
trying to run from the network share. Since the "mscorlib.dll" is on my
local PC, there must be some setting that caspol does not fix. I have
researched this to death and tried all sorts of settings to no avail. This
is really way too difficult for client/server applications.