This is a real long shot, but just in case...

If all of the following conditions are true:

• Your program is running in taint mode (perl -T).
• Your program already "untaints" CGI parameters via a regex pattern.
• These special characters are failing the regex.

Then perhaps one of the following conditions is true:

• Your program voluntarily quits via something like the die command.
• Your program performs an "unsafe" action with the tainted data, and the program automatically dies.
• The database connection specifies Taint=>1, and when you try to insert the tainted data the program dies.

If any of these are true, surely the web server's error log will tell you about it.

buckaduck