This is a discussion on is SetSystemTime atomic? within the Windows Programming forums, part of the Platform Specific Boards category; ? thanks....
From a programmers perspective, I would say that yes, it is. If two threads try to set the time to different values at any given point, one of them will get its time set, and the other will "loose" its setting of the time because the other thread got there afterwards. It will not set 19:46:32 if one thread tries to set it to 19:31:18 and the other tries to set it to 17:46:32.
Compilers can produce warnings - make the compiler programmers happy: Use them!
Please don't PM me for help - and no, I don't do help over instant messengers.