Strange Behavior on Posts Editing

I have been running a wp.org site for many years. Suddenly last week, I noticed an error when attempting to edit a post from within (such as trash the post or change the category). I tried several different browsers such as Chrome, an old Mozilla 5.0, and an Android 4.0.4 browser on my phone. I got the same type of response at various times. Another thing I noticed is that when I blog a post through my Mozilla browser (the same way I had been doing this for years), the same post can appear two or three times on the blog as different posts. Then when I try to trash the duplicates I get the error.
I have posted a screenshot of the error message which has the heading: HTTP Error 500.0 – Internal Server Error C:\php5\php-cgi.exe – The FastCGI process exceeded configured activity timeout. To see the complete error page please look here: https://dl.dropbox.com/u/28929276/errormessage.pdf
Please let me know what other information could be useful in this case.