Hi Heres your fix for your sound problem
Too fix the crackly sound you sometimes get in ut, when loading in XP, open advanced preferences (type preferences from console), open audio section, change effectschannels too 8, change latency too 60, restart UT.
The problem is caused by windows XP hd prefetching algorithm loading ut modules faster than the sound subsystem can initialise properly - hence it only occuring when ut loads from system cache, worked for me and many others 🙂
If it does/does not work for you get back to me for further solutions.