Make sure you read this if you run a wordpress blog. Never leave your .htaccess file permission at 777.
The only time where you might want to do that is setting up your blog for the first time or when a wordpress plugin (ex. W3 Total Cache) tells you explicitly that you need to change the file permission of .htaccess so that it can write to the file. On all other occasions, it’s wiser to set it to 644.
If your wordpress redirects stop working for no reasons, your .htaccess might have just been hacked.
As a general rule of thumb, use 644 for files and 755 for folders.