Navigation bar sticks on mouseout only in firefox..

Question

Any help and/or direction is greatly appreciated.

I have a dropdown nav bar that dynamically updates to load subpages using CSS and jscript. There's a Flash movie that the drop down menu will overlap on mouseover. Maybe this is causing a conflict with the mouseout function. However it works fine in IE this is only happening in Firefox. Firebug indicates the following error on the mouse over event. Is this the cause of the mouseout not working? I can't figure out what is wrong. Error and code snips shown below.

Security error" code: "1000 [Break on this error] else if (document.styleSheets[i].cssRules) {
skmmenu.js (line 62)

51 var toReturn = null;
52
53 if (document.styleSheets) {
54 for (var i = 0; i < document.styleSheets.length; i++)
55 {
56 var cssRules = null;
57 // IE
58 if (document.styleSheets[i].rules) {
59 cssRules = document.styleSheets[i].rules;
60 }
61 // Mozilla and others
62 else if (document.styleSheets[i].cssRules) {
63 cssRules = document.styleSheets[i].cssRules;
64 }
65 if (cssRules != null) {
66 for (var j = 0; j < cssRules.length; j++) {
67 if (cssRules[j].selectorText == ("." + className) && cssRules[j].style[propertyName] != null)
68 {
69 toReturn = cssRules[j].style[propertyName];
70 }
71 }
72 }
73 }
74 }
75 return toReturn;
76}

Thank you all in advance for you're time.