Beta problems

[Namespace]

I can't reproduce the error but with the current beta I get in a 
specific project this output:

----
Compiling Audio\Core\core.d...
D:\D\dmd2\windows\bin\..\..\src\phobos\std\array.d(15): Error: 
importing package 'memory' requires a 'package.d' file which 
cannot be found in 'core\memory\package.d'
import path[0] = D:\D\dmd2\src\ext
import path[1] = D:\D\dmd2\windows\bin\..\..\src\phobos
import path[2] = D:\D\dmd2\windows\bin\..\..\src\druntime\import
binary    D:\D\dmd2\windows\bin\dmd.exe
version   v2.064
config    D:\D\dmd2\windows\bin\sc.ini
parse     core
importall core
import    
object	(D:\D\dmd2\windows\bin\..\..\src\druntime\import\object.di)
import    
derelict.openal.al	(D:\D\dmd2\src\ext\derelict\openal\al.d)
import    
derelict.openal.types	(D:\D\dmd2\src\ext\derelict\openal\types.d)
import    
derelict.openal.functions	(D:\D\dmd2\src\ext\derelict\openal\functions.d)
import    
derelict.util.loader	(D:\D\dmd2\src\ext\derelict\util\loader.d)
import    
std.array	(D:\D\dmd2\windows\bin\..\..\src\phobos\std\array.d)
import    core.memory	(core\memory\package.d)
Building Debug\Audio-Core-core.obj failed!
----

If I try to reproduce it with a reduced test case, I get the 
right output:
----
import    std.array     
(D:\D\dmd2\windows\bin\..\..\src\phobos\std\array.d)
import    core.memory   
(D:\D\dmd2\windows\bin\..\..\src\druntime\import\core\me
mory.d)
----

What could cause the error? Any ideas? I have no idea...