The sound of my Windows-Vista-HP PC is unusually and tragically high.

To the Good People of the United Kingdom and Ireland, greetings and felicitations:

The sound on my PC's speakers is unusually high; indeed the sound issuing from my PC's speakers is tragically high to anyone with ears to listen. My PC is running on Windows Vista Home Premium and this problem came out of nowhere, which is to say I've never had this problem before. I've tried to adjust the speakers' settings so that the bass/treble inclines more to a bass sound, but it has not worked--I am still hearing everyone in high Chipmunk-like octaves. I even tried optimizing the settings in Windows Media Player and Windows Media Center in an attempt to correct this problem: alas, all to no avail. I am now desperate: this problem has caused Graham Parker & the Rumour on Youtube to sound like assorted new-wave castrati, which is an absolute crime against music for listening pleasure and all decent people of good taste everywhere. Can anyone out there (i.e. among the computer-knowledgable of the UK and Ireland) help me--and, of course, Graham and the Rumour--get this problem sorted out--and help prevent this trouble from recurring? I just can't get no protection. Paul/RDR040

Try rolling back your drivers, sounds like a driver issue.

Install Windows 7. It is almost like Vista, only less ghastly and less resource-hungry.

Otherwise, as hairyshit suggested, roll back the drivers, check if it was updated around the time the sound went chipmunk, or go into the sound settings and look for a setting that could do that. Failing that, replace the soundcard.