In IE6, any radio buttons are unchecked when toggling, losing their original value.
In FF2, radio button status is not changed and works as expected.

Removing line 404 from jquery-1.1.3.1.js causes just the opposite behavior (IE6 retains checked state, FF2 does not).

NOTE: this only occurs if animation is used. passing no arguments to jQuery's toggle() method does not cause the checked state to change in either browser. Passing either 'fast' or 'slow' does. Note this is only on the show() method -- hide() with animation does not cause this error.

Successful case (checked radio button remains checked in IE 6):

1. Hide Slow
2. Show w/o animation

Failure Case (checked radio button becomes unchecked in IE 6):

1. Hide w/o animation
2. Show Slow

Processor

Dual Core Intel Xeon 3.0 GHz

Quad Core Intel Xeon 2.66 GHz