To be quite honest, I can't see anything really wrong with your log, other than a "missing file" for BitComet in this line:
O9 - Extra button: BitComet - {D18A0B52-D63C-4ed0-AFC6-C1E3DC1AF43A} - res://C:\Program Files\BitComet\tools\BitCometBHO_1.2.8.7.dll/206 (file missing)
I would run HijackThis again and put a check mark on that line and click on "Fix". But, I can't confirm that it's related to your problem. Then again, it could be related in some way since BitComet is present as a Browser Helper Object.
Personaly, I would uninstall BitComet. It's a great way to catch nasties...