You may well be right I fear, though this is the first time I have encountered a problem with the apparent mismatch. I tracked the error using a debugger to an Rtl CriticalSection function.

And the following version which crudely approximates using fprintf() runs fine:

#! perl -slw
use strict;
use Inline 'FORCE';
use Inline C => 'DATA', NAME => 'IC_junk1', CLEAN_AFTER_BUILD => 0;

test( 'fred' );
test2( 'fred' );

__DATA__
__C__
//#include <stdio.h>

void test ( char* text ) {
    printf( "Got:'%s'\n", text );
    printf( "%x\n", stderr );
}

void test2 ( char* text ) {
    char buf[ 255 ];
    sprintf( buf, "%s", text );
    fputs( stderr, buf );
}
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So it does look like some difference in the CRTs that is responsible. I'd swear that I've used fprintf() from inline C before, but a quick scan of my files revealed none and I found a couple that called Perl_warn(), so maybe I encountered and worked around it some time ago and forgot.