QTR-Quadtone RIP

I'm running the latest Windows version of QTR and have run into an interesting problem relating to the size of the TIF file I'm trying to print. The file is from a 4x5 negative (scanned at 4000 spi on my Howtek) and is 539MB in size (no compression). When I open this file in QTRGui, a blank white square appears in the QTRGui File Open window where I would normally see a small thumbnail of the image. There is no error message or other indication that QTR has encountered a problem with the image (other than the blank thumbnail).

I went back into Photoshop and saved the same image to a different TIF file, this time compressed using LZW. Strangely, the resulting file size is now 710MB. I've seen increases in file size with compression before, but not this much! But the really strange part is that QTRGui successfully opens the larger TIF file (with LZW compression).

Both TIF files were saved as flat images without layers.

So my questions:

• Is there a known maximum size allowed for TIF files in QTRGui? (Is it different in QTR on the Mac?)
  
  
• Why would QTR open the larger TIF (with LZW compression) but not the smaller non-compressed TIF file?

For completeness of information, my workstation is running with 36GB of RAM and 4 CPU cores, so I think there should be no problem there.

Any ideas welcome.

Dave

More information after some further testing:

Print-Tool on the Mac can open both files with no problems. So this is clearly only a problem on Windows using QTRGui. My feeling at this point is that QTRGui is running into some kind of internal memory management issue when opening large TIF files. But I'd still like to know if there is any kind of "documented" (but maybe not largely known) limit on the maximum TIF file size in either QTRGui or Print-Tool.

Roy, any comments?

Thanks,
Dave