Fatal error in tablesort.inc line 114 when using project.module

Something in project.module doesn't play friendly with tablesort_cell() in tablesort.inc and it causes a fatal error on tablesort.inc's line 114 using PHP 5.0.4 on Win32. I'm not able to reproduce it on my PHP 5.1.0-dev Win32 machine. Whatever it is seems to happen before watchdog records the error to the mysql log, so I haven't tracked down the exact cause, but simply modifying the if statement on line 114 to add another isset() makes the fatal error go away. If php.ini's error reporting is turned off or set to log only, the fatal error causes the display to be completely blank.

The error was:

Fatal error: Cannot use string offset as an array in C:\........\includes\tablesort.inc on line 114

The error specifically refers to $ts['name'] (checked by breaking the if statement into multiple lines and turning on php.ini's error printing). Like I said, on my PHP 5.1.0-dev machine, the var_dump()s of $header and $ts look correct for both value and variable type. This only happens on project node pages except for /project.

Attached is a patch diff'ed against HEAD.