Symantec have released updates for Norton 360 and Norton Internet Security to make them compatible with Firefox 4, for details see http://community.norton.com/t5/Norton-Internet-Security-Norton/Firefox-4-compatibility-hotfix-is-now-available/td-p/428894

Thanks for the help I will follow up , Ian

Adding to TonyE...

The current official Hotfixs works only for FF 4.0. If you update to latest FF 4.0.1.. It Wont Works.!!! The fixs for FF 4.0.1 will be released by Norton very soon.. Till then if you plan to keep NIS tool bar working with FF 4.0 you have to opt for not updating the FF4,0 to 4.0.1.... There is workarounds to make the NIS tool bar appear in FF 4.0.1 ( visit Norton Community Forum...). But this are not official. Strongly recommend not to manually tamper with Norton system file unless you know what u r doing...

Norton-Toolbar-not-compatible-with-FF-4-0-1

Thanks Ary_My

Hi , thanks for your assistance , I have re moved v 4.0 & returned to 3.86 ? for awhile & no updates , just to settle down & it is all working again , I feel that there are far too many updates made ( not all are good ! ) and the result is non working add on`s etc` , I do the same in an older version of Thunderbird & nil updates I like it much better it had a great big useless bar in middle of my email message pane and result you can hardly see your emails properly , so thanks again , Ian