kernel compile message

Hello! Doing kernel testing, occasionally I started to get messages: mator@ttip:~/linux-2.6$ make -j olddefconfig; nice make -j20 && nice make -j20 modules # # configuration written to .config # SYNC include/config/auto.conf.cmd make[1]: /bin/sh: Bad address UPD include/generated/compile.h UPD include/config/kernel.release UPD include/generated/utsrelease.h It is not always "bad address" is shown, next time i run "make olddefconfig" it does not shows, but sometimes it shows... How do i debug this ? Thanks