I installed Lago

Check to see if you have the following audio compression codecs:Microsoft IMA ADPCM CODECMicrosoft ADPCM CODECMicrosoft PCM ConverterFor Win98/ME, open Control Panel, select Multimedia, Device Tab, open Audio Compression Codecs. If the codecs are present, click each one, select properties, and ensure the "Use this audio codec" is checked. If the codecs are missing, open Control Panel, Add/Remove Program, Windows Setup tab, select Multimedia, Details button, Audio Compression is selected, OK, and follow the instructions. You may need you Win98/ME CD to install the codecs.For WinXP, open Device Manager, open Sound, video, and Game Controllers, double-click Audio Codecs, select Properties tab, and check for the abbreviated codec names above. If the codecs are present, click each one, select properties, and ensure the "Use this audio codec" is checked. If the codecs are missing, insert your WinXP CD into the CD-drive and conduct a repair/reinstall.

I checked these codecs and all are Ok but the problem is still running...Thanks for your answer.

Have you tried uninstalling the LAGO Soundscape and see if the problem is fixed?It would really irritate me if an addon messed up my system and I would let the authors know about the program.