troubles with permalinks

I been installed wp 2.2.1, i changed my blog of server, and the entries was well imported.
I open the main page of the blog and all its ok, but when i click in a entry to comment or read all the entry, the permalinks (ugly) don′t work and all i can see is a white screen.
Next, i put a string in the .htaccess to see the error, and it was 500.

What is wrong? Note: I don′t want to change the permalinks.

—->Si alguien puede darme ayuda en espa?ol, bienvenida
para que vean el error, mi blog es https://www.elblogdeffuentes.cl/blog
No hay problema cuando se entra a las páginas fijas.