I changed permalinks on my wordpress installation and soon started getting white blank pages every time I published a post/comment or saved some settings in WordPress admin area. (needless to say the .htaccess was updated by wordpress during the permalink change)
E.g. ....categories.php would return a blank page, ....post.php would return a blank page, etc.
I reverted to the old permalinks setting and then my wordpress admin became inaccessible and wp-admin returned a blank page.
I restored a database backup from 26th april but still the problem remained! :O
At this point I created a fresh database and populated all tables except wp_options table (since it is the one containing permalink and rewrite rules settings) from my latest database and let the fresh wordpress install populate the wp_options field.
After this the wp-admin became accessible (thank god!) but even now I am getting a blank page when I post a comment/post or save some settings under wordpress dashboard.
I am a wordpress user since many years and very much savvy with it. I have left no stone unturned to fix this. Did everything! Is something wrong with my server!? In which case, will changing the server help?