i had a very similiar thing happen to me when i ran ubb on WebSiteProfessional from DeerField, no idea what happened, just stopped working after a few days so i gave up on the web server
try renaming the .cgi files to .cgi.txt and see if the open
(obviously only for a quick test do this:))
if they do its obviously somethin with the load and the sever just can't handle ur scripts being so popular and has crashed for a while, maybe give it a restart or, infact, make a few test cgi scripts
eg
!#blah blah
print "hi"
see if that works
if they do, then hmmm, if they dont, then good (in a way), just restart and maybe it'll work;)?