Internal Server Error on 1and1 server

Hi,
PROBLEM: After several page transitions I get the Internal Server 500 Error. Then after about 10 minutes it resets and the site is running again. It seems to be hardest on older IE Browsers.
I have read and tried several posts and I still have the problem. I don't know PHP so I have been trying to not go to crazy guessing in the htaccess file. Here it is if anyone can help I would greatly appreciate it and so would my users I am sure.
The change I made uncommenting the "rewritebase drupal /" Seemed to help but that could be just things settling in. The problem has existed since installation a month ago.

#
# Apache/PHP/Drupal settings:
#

# Protect files and directories from prying eyes.

Order allow,deny

# Don't show directory listings for URLs which map to a directory.
Options -Indexes

# Follow symbolic links in this directory.
Options +FollowSymLinks

# Make Drupal handle any 404 errors.
ErrorDocument 404 /index.php

# Set the default handler.
DirectoryIndex index.php index.html index.htm

# Override PHP settings that cannot be changed at runtime. See
# sites/default/default.settings.php and drupal_initialize_variables() in
# includes/bootstrap.inc for settings that can be changed at runtime.

# PHP 5, Apache 1 and 2.

php_flag magic_quotes_gpc off
php_flag magic_quotes_sybase off
php_flag register_globals off
php_flag session.auto_start off
php_value mbstring.http_input pass
php_value mbstring.http_output pass
php_flag mbstring.encoding_translation off

# Requires mod_expires to be enabled.

# Enable expirations.
ExpiresActive On

# Cache all files for 2 weeks after access (A).
ExpiresDefault A1209600

# Do not allow PHP scripts to be cached unless they explicitly send cache
# headers themselves. Otherwise all scripts would have to overwrite the
# headers set by mod_expires if they want another caching behavior. This may
# fail if an error occurs early in the bootstrap process, and it may cause
# problems if a non-Drupal PHP file is installed in a subdirectory.
ExpiresActive Off

# Various rewrite rules.

RewriteEngine on

# Block access to "hidden" directories whose names begin with a period. This
# includes directories used by version control systems such as Subversion or
# Git to store control files. Files whose names begin with a period, as well
# as the control files used by CVS, are protected by the FilesMatch directive
# above.
#
# NOTE: This only works when mod_rewrite is loaded. Without mod_rewrite, it is
# not possible to block access to entire directories from .htaccess, because
# is not allowed here.
#
# If you do not have mod_rewrite installed, you should remove these
# directories from your webroot or otherwise protect them from being
# downloaded.
RewriteRule "(^|/)\." - [F]

# If your site can be accessed both with and without the 'www.' prefix, you
# can use one of the following settings to redirect users to your preferred
# URL, either WITH or WITHOUT the 'www.' prefix. Choose ONLY one option:
#
# To redirect all users to access the site WITH the 'www.' prefix,
# (http://example.com/... will be redirected to http://www.example.com/...)
# uncomment the following:
# RewriteCond %{HTTP_HOST} !^www\. [NC]
# RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
#
# To redirect all users to access the site WITHOUT the 'www.' prefix,
# (http://www.example.com/... will be redirected to http://example.com/...)
# uncomment the following:
# RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
# RewriteRule ^ http://%1%{REQUEST_URI} [L,R=301]

# Modify the RewriteBase if you are using Drupal in a subdirectory or in a
# VirtualDocumentRoot and the rewrite rules are not working properly.
# For example if your site is at http://example.com/drupal uncomment and
# modify the following line:
RewriteBase /
AddType x-mapp-php5 .php

#--Not sure where these if to make them help.
#RewriteRule ^(.*)$ /CMS/index.php?q=$1 [L,QSA] -- to -- RewriteRule ^(.*)$ /index.php?q=$1 [L,QSA]
#"AddType x-mapp-php5 .php"

#
# If your site is running in a VirtualDocumentRoot at http://example.com/,
# uncomment the following line:
# RewriteBase /

# Pass all requests not referring directly to files in the filesystem to
# index.php. Clean URLs are handled in drupal_environment_initialize().
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !=/favicon.ico
RewriteRule ^ index.php [L]

# Rules to correctly serve gzip compressed CSS and JS files.
# Requires both mod_rewrite and mod_headers to be enabled.

# Serve gzip compressed CSS files if they exist and the client accepts gzip.
RewriteCond %{HTTP:Accept-encoding} gzip
RewriteCond %{REQUEST_FILENAME}\.gz -s
RewriteRule ^(.*)\.css $1\.css\.gz [QSA]

# Serve gzip compressed JS files if they exist and the client accepts gzip.
RewriteCond %{HTTP:Accept-encoding} gzip
RewriteCond %{REQUEST_FILENAME}\.gz -s
RewriteRule ^(.*)\.js $1\.js\.gz [QSA]

# Serve correct content types, and prevent mod_deflate double gzip.
RewriteRule \.css\.gz$ - [T=text/css,E=no-gzip:1]
RewriteRule \.js\.gz$ - [T=text/javascript,E=no-gzip:1]

# Serve correct encoding type.
Header set Content-Encoding gzip
# Force proxies to cache gzipped & non-gzipped css/js files separately.
Header append Vary Accept-Encoding