I also had the problem and found a work around.
It seems the problem is caused by the compiler Inline features. I remember that bug is caused when using inlined method and that method is too big.
This bug is exclusive for Delphi XE and seems was never fixed.
Check the next options of the packages
1) dwsLibRuntime package
- Delphi Compiler/Code generation/Code inlining Control = Auto or On or OFF
- Description/Build control/Rebuild as needed
2) dwsLib package
- Delphi Compiler/Code generation/Code inlining Control = OFF (this is the important thing)
- Description/Build control/Rebuild as needed
Recompile the packages and seems it works, it installs correctly and I can compile the DwsIdeDemo
I have posted also the solution to the bug report you made at: http://code.google.com/p/dwscript/issues/detail?id=419