June 2009 15" MBP - 5400 Hitachi Drive - Long BeachBall Pauses

Question

I've got a new late June Unibody 15" MBP with a 5400 rpm Hitachi drive and 4Gb RAM and I periodically experience long (30 or so second) freezes.
I suspected (and continue to suspect) Safari 4. It seems that this pause always happens while I am in Safari. When it happens it always freezes iTunes output. Sometimes other windows (like terminal or mail are fine, sometimes they are frozen.)
When these happen, I see no CPU load. I've started monitoring iostat to see if any i/o is going on and I see i/o go to zero when the freeze occurs. (I have an external drive attached for time machine, but in the example below it wasn't actively doing anything.)
disk0 disk2 cpu load average
KB/t tps MB/s KB/t tps MB/s us sy id 1m 5m 15m
49.77 14 0.68 0.00 0 0.00 12 12 76 0.48 0.48 0.42
12.34 28 0.33 0.00 0 0.00 10 10 80 0.41 0.46 0.42
14.43 91 1.28 0.00 0 0.00 18 12 71 0.43 0.46 0.42
17.96 35 0.61 0.00 0 0.00 12 11 77 0.83 0.55 0.45
11.87 44 0.52 0.00 0 0.00 13 11 76 0.71 0.53 0.44
7.87 297 2.28 0.00 0 0.00 13 12 75 0.82 0.56 0.45
*0.00 0 0.00* 0.00 0 0.00 12 11 77 0.77 0.56 0.45 (iTunes is frozen during these samples)
*0.00 0 0.00* 0.00 0 0.00 3 8 89 0.65 0.54 0.45
86.55 2 0.19 0.00 0 0.00 5 9 86 0.55 0.52 0.44
I've noticed that it occurs more often when I use my higher power GPU.
I've tried resetting Safari and disabling top sites (although I haven't been successful at that.) I've also reinstalled Safari.
Any ideas?
Thanks,
John

Answer 1

It does appear that I am running that update. From System Profile:
Hardware Overview:
Model Name: MacBook Pro
Model Identifier: MacBookPro5,3
Processor Name: Intel Core 2 Duo
Processor Speed: 2.8 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 6 MB
Memory: 4 GB
Bus Speed: 1.07 GHz
Boot ROM Version: MBP53.00AC.B03
SMC Version (system): 1.48f2
Serial Number (system): W89236DU644
Hardware UUID: B06E8157-1F18-5D8B-AC83-6D515B508B3B
Sudden Motion Sensor:
State: Enabled
Thanks,
John