I get this all the time...just started 2 weeks ago...I thought it would go away, but I guess not. I only get it on this website.

 

Are you using the latest version of Firefox? I've never seen that. Try adding their Trublock Plus and see if it helps.

 

Where were you trying to go? Post the URL and I'll try it.
As it stands, you simply entered a bad request, sometimes old links
have changed address and etc. Looks like it might be a .pdf.

 

Just trying to navigate this website...very likely to get it when I hit the "Submit Reply" button right now...if I do get it, I simply refresh the page and it goes where I was going...If I get it when replying like now...I may or my not have to retype everything....makes no sense...do have latest version of Firefox...doesn't do it on any other website...just here

 

Well, you have a tab open that shows "Bad Request," I can see
it in the picture, so where were you trying to go with that tab?

 

If you look at the address bar in the screen capture, at that time I was going to:
www.hdforums.com/forum/softail-models-7/

 

Must have corrected itself, worked fine for me.