blinking, flasing tabs
Tabs have started blinking and flashing every time I try to open a new tab or web page. I have tried everything I know to stop this, including reinstalling Mozilla after getting rid of the previous one and following directions listed on the Mozilla help pages (Alice Hyman, etc.), confirming that toolkit.cosmeticAnimations.enabled is set for "false." I am using an older MacBook Pro that is running OS X 10.11.6 El Capitan and Firefox 7.0.1 (64-bit), and this problem just started on Nov. 5, 2019. The flashing stops when I am doing nothing with tabs, but, if I even move the cursor across the tab bar or open a new tab, the flashing starts again. Is this caused by malware? If so, how do I find that malware and remove it? Thanks.
Additional System Details
- Shockwave Flash 32.0 r0
- User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:70.0) Gecko/20100101 Firefox/70.0