I have had issues with playing streaming Flash audio & video since installing LM7 over LM6. This manifested itself as skipping audio or video or popping noises within the sound track.
I followed lots of advice from the Ubuntu & Mint forums for days (including the link from Clem at the top of this forum) to no avail.
As I was having lots of issues with sound I went to Control Centre -> Sound and ran through all the audio tests and found that none of the options gave a satisfactory audio test apart from ESD. All of the "failed" tests had a "popping" noise on the audio.
After more messing around I came to this link http://ubuntuforums.org/showthread.php?t=1085632 and followed the advice at the bottom of the page which was:
Add this line to /etc/modprobe.d/alsa-base:
options snd-hda-intel position_fix=1 model=lenovo
Hey presto it all works. Video fixed as well as audio. In Control Centre all sound settings work fine so I've set them back to automatic and everything is now working just fine.
Just thought I'd post this up as a number of people seem to have this problem.