I got some more information about this problem :
The C compiler (CW6.3) generates the assembler instruction STRLDSR #2700 at the begening of an interrupt routine.
If I put the same assembler instruction in an assemby code, I get the message :
"Instruction not legal for curent target processor" , which is MCF5329.
How does it come that the C-compiler generates the STRLDSR instruction and in the same small project, the same instruction is refused in an assembly file ?