I have loaded the windows 32 bit version 4.15 on different hardware (2 laptops, 2 quad cores with plenty of memory) typically with XP systems, one with Windows 7. What usually happens is, I can load or create a small song, maybe with about 4 3x Oscillators and it seems to work OK, once I load one of the large demo songs or add more oscillators, or drums, it hangs. The menu interface works, it just won't play a song. I can exist out of the GUI and restart LMMSV4.15, but it just hangs again once you start adding instruments.
I downloaded V4.13 as per others recommendations, and it seems to work just fine.