Core.a not found?

I'm trying to compile a program in the arduino IDE without using the arduino core library (i e just plain C code), so I can control all hardware timers etc myself. So I created a new board in boards.txt and set the .build.core=blank. But when I try to compile I receive the following error:

avr-gcc: C:\DOCUME~1\DAHE~1.TRI\LOKALA~1\Temp\build40524.tmp\core.a: No such file or directory

Couldn't determine program size: C:\Program\arduino-0015\hardware/tools/avr/bin/avr-size: 'C:\DOCUME~1\DAHE~1.TRI\LOKALA~1\Temp\build40524.tmp\test.hex': No such file

Any ideas? Can this be related to the release notes saying something about core.a in the latest release?

I'm trying to compile a program in the arduino IDE without using the arduino core library

The two are tightly coupled; I seriously doubt this will work.

-j