Re: How do I get rid of the Facebook blue box on my Firefox pages???
Start Firefox in Troubleshoot Firefox issues using Safe Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).
Don't make any changes on the Safe mode start window.
Do a malware check with some malware scanning programs on the Windows computer.
You need to scan with all programs because each program detects different malware.
Make sure that you update each program to get the latest version of their databases before doing a scan.