Instead of defrag-ing, I would run a chkdsk /f first, just in case the file system is damaged ... simple fragmented files normally shouldn't pose any troubles since we left Win9x behind ... .
Maybe add a /r, because a NTFS file system does not damage itself normally ...
And while you're at it, maybe get yourself the "Ultimate Boot CD" , and run some RAM diagnostics first (Memtest-86 / plus). I advise doing that every couple of months anyway - RAM or motherboard starting to show faults isn't something you'll spot at once, but only when things already got really bad - and some irreplacable data got lost
But then, most likely, it's only the OOB that has some value in it that scenhack does not like at all. Therefore, instead of attaching the scenario file, better attach the OOB file for the developers to check !
Re: Bug in Scenhack?
Threaded Mode