Debian used an extremely old compiler on their default 2.2.20 kernel (gcc 2.7.X). They then shipped their distro with a newer, but still almost ancient compiler (2.95.3). These compilers, AFAIK, are not compatible.
The solution would be to recompile Debian's kernel sources with your gcc 2.95.3 (but change the top-level Makefile's EXTRAVERSION string to be something, like -custom or whatever, so that you don't overwrite your old modules directory).
Well... you probably want to double check that first -- do a cat /proc/version and a cc -version to get the version of gcc used to compile the kernel, then the version of gcc currently installed. If the first is 2.7.X and the second is 2.95.3, then this is your problem.