[TYPO3-english] What does these warnings mean?

[Ronald Wiplinger (Lists)]

Sometimes I see warnings like:


*Warning*: mysql_fetch_assoc(): supplied argument is not a valid MySQL
result resource in
*/home/elmit1/public_html/typo3_src-4.2.1/t3lib/class.t3lib_db.php* on
line *808*

*Warning*: Cannot modify header information - headers already sent by
(output started at
/home/elmit1/public_html/typo3_src-4.2.1/t3lib/class.t3lib_db.php:808)
in */home/elmit1/public_html/typo3_src-4.2.1/typo3/template.php* on line
*632  


What do they mean? Is it a programming error that causes that or a
network error?

bye

Ronald
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