It is unfortunately hard to troubleshoot intermittent problems only occurring on a single (or few) systems.
1) Ensure you have the latest audio drivers installed.
2) Try changing the speed of the ATC in EditVoicepack. This will change all the generated sound files, hopefully no longer generating the data causing the problem.
3) This is where it get tedious - try deselecting parts of the modifications EditVoicepack makes (for example, try not changing ATC phraseology, then try not adding callsigns). Slowly it is possible to narrow down which modification(s) cause the problem. This is not a fun thing to do, so I hope 1) or 2) will solve the problem.