I looked over your code at it looks like it shoud be OK to me.
I Tried to compile it with my VC 71 system using boost 1.3 (cvs HEAD)
and I got an error at the following line:
class ABC : public IA, public IB, public IC
\BoostHead\libs\serialization\test\test_zmisc.cpp(85) : fatal error C1001:
INTERNAL COMPILER ERROR
(compiler file 'msc1.cpp', line 2701)
Please choose the Technical Support command on the Visual C++
Help menu, or open the Technical Support help file for more information
which looks to me to be an artifact of the test system. I'll look some more
if I can get the chance.
Robert Ramey
"Michel Pineau"