I am experiencing the exact same problem on two brand new toshiba laptops.
Definitely wi-fi related, my propblem goes away if I disable wi-fi - But it seems to be much better on some wireless networks than others - I suspected the security encription - I changed to WPA 2 from WPA and things seemed to get better - but then after a week it went back to being bad again.
Skype, CD, MP3 on the laptop, youtube - all give the problem
Did you have any luck on solving the problem?
laptop one portege R835 win 7 32 but
patop two tecra R850 win 7 64 bit
Regards
Brett