The UUID RFC is from 2005, but they're also documented in the ISO/IEC 11578:1996 standard.
As I mentioned, a good type-1 implementation uses a counter to simulate a higher resolution system clock to get around the system clock resolution limiting scalability. Also, I'm guessing you're generating type-4 (random) UUIDs instead of type-1 (MAC address and timestamp), right?
My point is that if you're generating UUIDs rapidly, check that you're either generating type-4, or that you're using a high-quality type-1 implementation that simulates a higher resolution clock using a counter.
I definitely didn't had issues the last 10 years ( .net )