Editing php.ini

I attempted to change the file upload size limit by creating a php.ini file in my website root. I put these lines in it:

upload_max_filesize = 100M
post_max_size = 100M
memory_limit = 100M
upload_tmp_dir = 100M
max_execution_time = 50000

This works and I see the change take effect by looking at phpinfo.php.
What happens, however, is that all the other options for php seem to revert back to default or something. Safe_mode gets turned on and I start getting errors on the gallery pages. I tried adding "safe_mode off" but that only gets rid of some of the errors. Others still seem to pop up. The problem gets resolved if I just delete the php.ini and all the php settings revert back to the server default. Any solutions to allow me to alter file size limit but still keep the other php settings normal? Thanks.

-Andrew