File xxx could not be saved, because the source file could not be read.

Hello,

I have been bedeviled for a long time by an OS X Mozilla bug that 
appears to have fallen through the cracks.  The bug is that you click on 
a link which needs to be opened by a helper app, and the launcher for 
the helper app gives the error message "<temp file name> could not be 
saved, because the source file could not be read."  I can sometimes work 
around this problem by restarting Mozilla.

Googling turned up many instances of users reporting this bug, and a 
search in Bugzilla turned up at least one report.  But the solution to 
all of these situations, including the bug report, was that the Mozilla 
install was corrupted and needed to be redone.  I have reinstalled, 
cleaned and scrubbed a number of times without any improvement, so I 
don't believe that is the correct diagnosis in this case.

I can keep working around the problem by using other browsers, but since 
Mozilla is my preference that isn't appealling.

Thoughts?

Thanks in advance.

- Lucas Gonze