Firefox automatically keeps switching to the initial window of Firefox opened

Recently I have been issues with switching between windows of Firefox. No matter how many times I try to Alt-Tab or click on another window it momentarily goes to that window before switching back immediately. The only work around I found is to click a window of some other software and then click the window I want to work on in Firefox. Doing this is not making it switch back to the older window of Firefox again. Please help me in fixing this issue. It's making it nearly impossible to work on Firefox due to this.