We tested pretty extensively in Firefox, but there's always things that can go wrong. Also if you think you have any info that will help us fix it, hit up the Contact Us link at the bottom of http://help.grooveshark.com/
Well, if I run FF from a different account it seems OK, so my guess is that the scripting is not playing well with Greasemonkey or Firebug or some other add-on.
So, on the one had, the trouble is at my end, but on the other hand most sites have no trouble with my add-on arrangements, so there's something that's at least a little sensitive in the GS scripting.
Follow up: Disabled add-ons to see if one was causing trouble, and it's Flashblock 1.5.13. Usually it shows a placeholder you can click to allow the Flash object to run, but it doesn't seem to show for me.
Probably best to make the default on the homepage somewhat more readable though.
Who's your target market for this product? The styling on the homepage is pretty tech/minimal, but if you're going after the home user maybe something more light-hearted would be appropriate? I can see people using the videos to create custom Christmas or Birthday messages, but style-wise that market probably respond better to something more like: http://www.moonpig.com/uk/
I'm in the same position as you, looking for a good linux laptop. Haven't found one yet.
I had a chance to play with Thinkpad t410 and x201 and I have to say they weren't as good as I expected. There was very strange whining noise emitting from the cpu area and displays were just awful. I heard that the noise problem persists with newer Core i3/i5/i7 Thinkpads.