Error in external

[John Craig]

I wrote a small external a while back after Mark Waddington's newsletter 
article.  The external seems to work fine most of the time, but every 
once in a while throws an error.
The variable watcher tells me that the temp vars that were set prior to 
calling the external function have mysteriously emptied.  Has anyone 
else experienced anything similar with externals?

(WindowsXP, Rev. 2.7.4 , VC++ )

Thanks,
JC