Posting Box Problem

Is this problem with WP or Hostgator do you think.

Over the last week or two the size of the posting box has reduced from the nominal 20 lines to about 5 lines on all 5 of my WP sites and all at the same time. Resetting this option has no effect.

It makes editing very difficult.

Is this a common problem or just Hostgator perhaps.

Regards
Lee