I ran into a problem with FireFox about a month ago where I'd get an error popping up regularly saying:
"The procedure entry point ??0NS_ConvertUTF16toUTF8@@QAE in xpcom.dll not found."
The problem persisted with the 1.0 release. I finally found a reference on Google stating that I should get rid of the ActiveX plugin. I deleted the plugin and the problem is solved. I really enjoy the browser, especially the tabbed browsing feature (not to mention the security and performance considerations).