The two cases for software was that "crack" for XP and another was malware. The crack stopped time so the activation would not expire. Everyday users are very confused about that one. The other was malware which I suggest Grif's advice at 7726-6132_102-5098912.html?tag=posts;msg5099421
You write about nist sync. Try it without that too.
XP with SP3 on Inspiron laptop. Windows clock won't update. Even when manually reset, time is okay for a while, then stops. Linked to NIST for accuracy. Doesn't matter if plugged in. Any ideas? Thanks.