After a long time of testing I could solve an well known issue of the TYPO3 extension a21glossary. The extension should link some definitions, acronyms, etc. to the glossary, like this -> IRC <- example. But sometimes it doesn't do it.
The problem was a wrong regular expression which sometimes matches to long text. I could solve this issue but I don't know where to commit the patch. So I'm publishing it here 
I have contacted the TYPO3 mailing-list and have asked where to commit this patch. So there is a good chance that this patch will be applied in the next release of the a21glossary extension.
I have uploaded a second version of the patch which prevents to hang up if there is a long document with no <a> or </a> tags in it.
There was an issue if there are more than one keywords nested into <a></a> tags and one of them is an acronym.
There was an issue if a link should be generated followed by an non-linked <acronym> or <abbr> tag.
Thanks a lot!
You made my day, thanks a lot for this patch!
No Change
I'm not sure, what i did wrong but finally nothing changed n my webpage after applying your patch.
do you have an idea what could be the problem in my case?
Try this...
First check if you really have copied the patched file to the correct location of your Typo3 installation (typo3conf/ext/a21glossary/class.tx_a21glossary.php).
If this is the case then clear all page caches of your site!
Dirk.