OFFICIAL Display Issues, Preferences, Sounds and Music

[slartismum]

I think that I have asked this before but forgotten the answer. Even though I have done a memcache, restarted the computer and searched for malware, when I work my NBs farms the fields disappear and only show when I scroll over them with the mouse. As you can imagine this makes farming difficult.
I am using Firefox as Chrome no longer works for me. Other games I play (Family Farm etc.) are not affected and my own farm is fine.
Could you suggest anything further that I could attempt to fix this, please?
My ID is 0000035722597