1998.04.07 00:44 "RE: libtiff isn't closing all of the file handles on NT ?", by Dean Grimm
I too have experienced the problem and believe it to be a problem with memory mapped files. Try specifying TIFFOpen("file.tif", "ru") which tells the library to use standard file I/O and the problem disappears. Unfortunately, I haven't as yet had time to debug the code.
Hope this helps,
Sr. Software Engineer / Cortron Corporation