No way to fix it. It is technically not a "bug" per se with the game. The game was written in the Windows XP days, and you did not shell-out to Windows and "lose" the audio and / or video "stream" the way you do with Windows Vista and all later versions. It has to do with Windows handling programs and resources as "virtual", and assigns "addresses" for the system resources to the programs, such as the video card and sound card, but Windows still retains control of the devices. In Windows XP, those "addresses" were static and did not change.
In Vista and later, if you "shell-out" from the game to your Windows desktop, the OS might assign a different "address" for the resources that the game is using. Newer games "refresh" their "addresses", whereas the older programs don't. The game still expects to find the sound card and the video card where they were, as well as its temporary address space, but they might have been "moved" and now has a new "address". When that happens, you end up with strange game behavior, the most common being the CO2 level sticking, as well as audio looping and other anomalies. The only "fix" is to not shell out to Windows by use of the <Alt><Tab>, or <Ctrl><Tab> or <Windows> key combinations. If you need to go to Windows, save and exit the game, then use Windows...
