For longer time I experiences unpleasant slow freeze of IE 7.0 each time I opened link in new tab and also closing IE took 20 and more seconds to finish.
When I started IE without add-ons (use right click on IE icon), it worked as expected. So I hunted down for the specific plugin and I identified JSQIEStartDetectorImpl Class (jqs_plugin.dll) as the source of troubles. I dod not found any useful information on Internet, but this seems to part of Java Quick Start introduced with Java 6 Update 10. The problems are also present in Java 6 Update 14. Maybe it manifests itself only on certain installations (I have Windows XP 64-bit), but anyway the plugin is disabled now I IE works fine.