Has anyone recently upgraded their version of Firefox and now having trouble with the text being a bit blurry and doesn't clear until you move the cursor over it?

I've had this problem for the last few days and been on the Mozilla forums where lots of other users are having the same problem but the suggested fixes haven't worked for me. Any ideas? It seems to be a big problem when I'm on this forum and looking at quoted text in posts.

Any ideas would be a big help as it's doing my head in now!!