I think everything is OK is with my MT installation, except that internal server
error which
happens only when I rebuild templates containing feeds.app code. If I remove the
code from
the templates, then they rebuild normally.
My webhost has some limitations CGI limitations:
Processing time: 12 seconds @ 100%
Memory 16384KB (16MB)
Number of processes 12
I guess it's better to look for help in the MT forums.