Error 500: Internal Server Error

[forum4ttt]

I keep getting the following error when I post a new topic...using IE or Firefox.

'Error 500: Internal Server Error
The server encountered an unexpected condition which prevented it from fulfilling the request.

The problem is on the server side, not with your browser or the address. Most probably, a certain service (e.g., Tomcat engine) is down. Please contact your webmaster.'

This error only happens with some text and will happen even with a new thread not just during modify where it first occurred.

I thought it might be the SpellCheck feature so I turned that off.  Still get the error
............

this is really weird....by process of elimination I have determined that adding the word "from" to the text causes the 500 server error.

Initially the problem started with the following text...I then eliminated letters and just "from" caused the errror.  I notice that I can post the problem text here without a problem.  What is going on here?

"Right click on TapeReaderANDTrendReaderAssembly.zip and select 'Save Link As'. Save the file to your desktop so it is easy to find. DO NOT unzip the file.  Also download 'TrendReader template.xml' to your desktop. NOTE: This template sets the Properties for the chart for best viewing. It also removes the Toolbars to save space.  To add indicators/strategies to the chart after the template is added, right click in the chart and select options from there."

I can literally just remove the second last word ("from") from the text and it will post.  When I add back "from", I get the server error.

[forum4ttt]

I created the following thread to test my theory and literally the one word causes the error...over and over again....take it out, fine...put it in, error...
............................

replacing the **** below with the word "from" replicates the error

Right click on TapeReaderANDTrendReaderAssembly.zip and select 'Save Link As'. Save the file to your desktop so it is easy to find. DO NOT unzip the file.  Also download 'TrendReader template.xml' to your desktop. NOTE: This template sets the Properties for the chart for best viewing. It also removes the Toolbars to save space.  To add indicators/strategies to the chart after the template is added, right click in the chart and select options **** there.

[forum4ttt]

I do not know if this is related however from my website stats I notice that .../forum/index.php made 127 unsuccessful (404) hits on a page that does not exist .... /forum/mydomainname

[forum4ttt]

Infinology tech support resolved the problem as follows:

'The problem has been fixed now. This issue often causes due to Mod_security enabled on the server.I have disabled it for your forum by adding a .htaccess with mod_sec disable code.'