Hi Sgone,
It seems that you are having this issue from quite a long time :
Sound issues when publishing to Ovi
There are number of issues with flash lite stub like one cannot change volume by volume keys in Flash Litre stub, Sometimes pressing red key doesnt close the application and few others.Some of these issues are solved in SWF2GO.However, This issue is also discussed few times before but not solved yet (according to my knowledge). What u can do is try an alternative to Flash Lite stub i.e SWF Launcher but it also has some limitations like heap size cannot be changed, relative paths for loading swf files cannot be used . If u have some knowledge of Symbian C++ then u can create a SWF Launcher for free by reading articles in Forum Nokia Flash Lite wiki.
Btw, you can also contact Faisal (a FNC & a lead developer of SWF2GO) which may have a solution to this issue.
Best Regards,
SajiSoft