what do you mean by "I downloaded LAME and placed the DLL on my path"? LAME comes with Switch, you don't need to download it - is there somewhere you read on our website that said you had to download the LAME .dll ?
Try downloading Switch 1.05 and see if it makes any difference. Uninstall 1.04 first though.
Also, Switch uses DirectX to decode your mp2 files, so if it is working one minute and not the next, check your DirectX installation hasn't become corrupted somehow.