I sailed from Midway, January 14, 1943 merc, went to Kyushu via the Mariannas, and now I'm going northeast along the coast, pretending to be the Galloping Ghost... no issues whatsoever thus far. I have noticed one thing though: if you use TC over 2048, the audio stream can and does go whonky at times, just like in Stock... I have not sunk anything yet, thank you very much BuOrd... sheesh. Two under-runners, and two klunkers... No explosions even.
What are your system specs merc4ulfate? Are you certain that the LAA is set correctly on the SH4.exe file? Do you ever "shell-out" to Windows with the Windows key, the <alt> or <Ctrl><Tab> combinations? Even if your game is "paused"