Seems those using Norton have started having problems since Thursday’s (5/5/16) update. Seems they get double posts in chat and clicks don’t work first try.
The fix is to uninstall, run the Norton removal tool, and reinstall.
I am seeing lots of people in the Firestorm Support group asking for help with the issue. The problem happens on all viewers – LL viewer, Firestorm & Singularity have been tested.
In trying to dig up more information on the problem I found the SL JIRA was down… I couldn’t get a page to come up. But, then I tried Firefox, I can get the pages to come up in Firefox. Weird. I was using Chrome.
The report I was looking for is: BUG-11891 – Text duplicates in local and IM. Movement lags and sometimes clicking an item requires multiple clicks. Reading you’ll find that group announcements are posting twice too.
Kyle Linden posts the fix the Lab is going with.