For those getting :d instead of :D try going to User CP - Edit Options - then down to the bottom of the page and in the Miscellaneous Options box change Message Editor Interface to Enhansed Interface - Full WYSIWYG Editing. Have never had a problem with it.
It is possible that the other problems are coming about due to lack of ISP connection speed, memory and more likely than not some other program/s you may be running that aren't 100% compatible with the forums. Firefox seems to be a bit of a culprit but that doesn't mean it is the problem.
Hope this is of some help.
Cheers - Neil :)
PS They say that Full WYSIWYG Editing may slow things down a bit especially if you are on dial up, but I have used it on dial up as well as ADSL and it always works well and found it doesn't make too much difference to speed.