All tests pass but I get this error message when trying to access the control panel. Any ideas?

Software error:
(Maybe you didn't strip carriage returns after a network transfer?)
For help, please send mail to the webmaster ([email protected]), giving this error message and the time and date of the error. Content-type: text/html

Software error:
cp_common: [Fri Nov 16 11:20:45 2001] : (Maybe you didn't strip carriage returns after a network transfer?)
For help, please send mail to the webmaster ([email protected]), giving this error message and the time and date of the error.