XCode Build hang

I'm building a standard Tool (i.e. command line app) in XCode and
occasionally it will hang doing a build. By this I don't mean XCode
stops, all windows and controls are still responsive but it does not
finish the build. The Build button is greyed out and I cannot quit
the app since it asks to stop the build, cannot and comes back and
asks again to kill the build. The only cure so far is to kill XCode,
when I do that and bring it back up again it works fine and finishes
the build.

The code I'm building is all in C and has over 300 files. Also this
problem only happens when building on a Lime iBook with 320 Megs of
RAM running under OS X 10.3.2. If I use a dual 533 MHz G4 running
10.3.2 it builds much faster (obviously !) and had never exhibited
this problem.

This problem is more an annoyance since nothing appears to be
destroyed when it happens but anyone have any suggestions to fix it ?

--jim