記事ブロックのdt、ddタグに「and」を書くとエラー

記事ブロックのhtml画面で下のように「and」という文字を入れると403エラーが出るようです。
（ddタグに入れても同じ現象になります。）

＜ｄｌ＞
　＜ｄｔ＞and＜／ｄｔ＞＜ｄｄ＞＜／ｄｄ＞
＜ｄｌ＞

# concrete5 Version
Core Version - 5.7.5.6
Version Installed - 5.7.5.6
Database Version - 20151221000000

# concrete5 Packages
Block Designer (1.3.13), Vivid Simple Accordion (1.0.1).

# concrete5 Cache Settings
Block Cache - Off
Overrides Cache - Off
Full Page Caching - Off
Full Page Cache Lifetime - Every 6 hours (default setting).

# Server Software
Apache

# Server API
cgi-fcgi

# PHP Version
5.4.27

# PHP Extensions
bcmath, bz2, calendar, cgi-fcgi, Core, ctype, curl, date, dom, ereg, exif, fileinfo, filter, ftp, gd, gettext, hash, htscanner, iconv, imap, ionCube Loader, json, libxml, mbstring, mcrypt, mhash, mysql, mysqli, mysqlnd, openssl, pcntl, pcre, PDO, pdo_mysql, pdo_sqlite, Phar, posix, readline, Reflection, session, shmop, SimpleXML, soap, sockets, SPL, SQLite, sqlite3, standard, sysvsem, sysvshm, tidy, tokenizer, xml, xmlreader, xmlrpc, xmlwriter, xsl, zip, zlib.

# PHP Settings
max_execution_time - 30
log_errors_max_len - 1024
max_file_uploads - 20
max_input_nesting_level - 64
max_input_time - -1
max_input_vars - 1000
memory_limit - 128M
post_max_size - 5M
sql.safe_mode - Off
upload_max_filesize - 5M
mysql.max_links - Unlimited
mysql.max_persistent - Unlimited
mysqli.max_links - Unlimited
mysqli.max_persistent - Unlimited
pcre.backtrack_limit - 1000000
pcre.recursion_limit - 100000
session.cache_limiter - no value
session.gc_maxlifetime - 1440
soap.wsdl_cache_limit - 5