error report appears directly below widgets on left sidebar

error report shown directly beneath left sidebar which includes: category drop down list, archives and author list.

error report is displayed in the left sidebar.

error report relates to path
\wp-includes\formatting.php
line 913 warning strtr(0) expect parameter 1 to be a string.

I don't see anyway to troubleshoot this problem without ability to bkpt and set a variable watch ??

WP 2.9.1
Atahualpa 3.4.6