thunderbird won't start - script error iterator.utils?

thunderbird has been working perfectly, but just recently it has stopped starting up properly.

a script error appears. it is unable to finish a script called iterator.utils

my profile is on a server. my desktop with a wired connection is still fine, but two laptops which use wireless connection now have the script problem.

fault happens in thunderbird's safe mode.

i've run out of ideas.

james
October 2010