FPE"s function for changing user password no longer works

Hello!

Our provider started having problems with FrontPage Extensions a few weeks
ago. Now most of it finally works, but FPE's functions to make user's able to
change their password on their own is no longer working and their technicians
say they cannot figure it out. The file that should show up should look like
this:
http://hudson-properties.com/_vti_bin/passwd.htm.
Instead we get the following message (have also tried to recalulate
hyperlinks etcetra on the web site):
"Internal Server Error: The server encountered an internal error or
misconfiguration and was unable to complete your request. Please contact the
server administrator, webmaster@gronlandshagen.com and inform them of the
time the error occurred, and anything you might have done that may have
caused the error. More information about this error may be available in the
server error log. Apache/1.3.37 Server at gronlandshagen.com Port 80"

We indeed need to make this work, but don't know where to begin.
--
Ivar