We just switched from kix32 ver. 4.53 to ver. 4.63 for Win7 support.
The sidtoname() function seems broken for resolving sid's for domain users and local users. (returns error 1332 (ERROR_NONE_MAPPED): "No mapping between account names and security IDs was done.") It now seems to work only for well-known sid's (groups and users).
In kix versions 4.51 and 4.53 this function worked perfectly.