_sntprintf is aliased to swprintf which causes an Access Violation in Win32. A single #define fixes it.
#define swprintf _snwprintf // remove this to make the following code crash
CHAR b[5]; memset(b,'x',sizeof(b));
n=snprintf(b,NELEM(b)-1,"WorksFine");
WCHAR a[5]; memset(a,'x',sizeof(a));
n=_snwprintf(a,NELEM(a)-1,L"WorksFine");
n=swprintf(a,NELEM(a)-1,L"AccessViolation");
Now if only you library makers could get your maxsize handling, \0 termination, and return values all consistant.
[edit: this seems to be fixed in the released version]