Can’t Post Text With Yellow Highlighting

I am not able to copy and past text with yellow highlighting (didn’t try other collors) into New Posts, from MS Word or other sources. I have been able to post with highlighted ares in the past, but also experienced times in the past when I couldn’t make the highlighting work, then for reasons I don’t understand I was able to post highlighted text again.

I need help with this problem, is it some thing I am doing or is the problem in WordPress 2.8 or both. I experienced this also before I upgraded.