Bizarre Slowness/sound problems

I just created my account and installed SL today. When I launched the app, I had the most odd behavior.

The login screen is fine, and after logging in it loads up, I got a dialogue about streaming music and another asking about gender which I answered immediately before it had finished loading fully. The game then froze, causing me to lose my mouse controll entirely, and my music playing through itunes began to do this weird echo-stutter thing, echoing a small section of the song about 10 times all overlapping and then jumping to the next part of the song abruptly and echoing again.

I was able to use alt-tab to switch to itunes, and then alt-Q to quit (I thought it might be interfering) but the computer continued to appear mostly crashed. I alt-tabbed back to SL, and used alt-Q to quit that, and instantly my machine returned to normal. I've tried re-launching the application several times, and each time the behavior is identical, and can only be fixed by quitting the game.

System specs:

Mac OS X 10.4.4
Dual 2.3 Ghz G5
1.5GB ddr2 sdram
Nvidia gforce 6600 video card

Game version that I have is 1.9.0.18

I'd really like to be able to give this game a try, can anyone give me any tips on how to get around this problem?

No replies at all? I have a stock g5 with a relatively fresh install of the OS, so I don't think this is hardware or software conflict related. If anyone could give me any clues at all of something to look at, just somewhere to get started, I would be really happy.