[Chrelion]

This has been happening with 5.5.4 and the latest 5.5.3 builds. I'll be running Omniweb, everything's fine - and maybe I try to open a new tab, or close an existing one (there's really no consistency with this problem). Anyway, OW locks up. So, I try force quitting it from the Dock - and when I check in Activity Monitor, there's nary a trace of Omniweb. But the icon's still in the dock - with the little running indicator next to it. I could try force quitting it or killing it numerous times, but according to OS X and the terminal, it's not running. Eventually my entire system grinds to a halt and I have to shut it down manually - since it takes forever to interact with menus. I'm pretty stumped here and any advice would be great.
System:
MacBook Pro 17" 2x2.16
1 GB RAM
APEs installed:
ClearDock
IceCoffEE
Instant Hijack Server
Plugins:
A float, JavaPluginCocoa,megazoomer,flash player,flip4mac wmv,iphotophotocast,quicktime,verified downloadplugin, quart composer

Anything other info that'd be helpful in diagnosing what's going on here?