> Could you build in some method of implementing fuzzy 
logic, 
> such as 'if uppercase fails, try lowercase', or 'if .htm 
> fails, try .html'?
URIs are case sentitive in httrack (not hostnames) ; 
therefore index.html and INDEX.HTML will be saved as two 
different files by httrack. Besides, httrack considers that 
index.html and INDEX.HTML are the same local ressource 
names, and therefore will save them with different names.

Example:
(remote name)   (httrack local name)
index.html      index.html
INDEX.HTML      index-2.html
Index.html      index-3.html
INDEX.HTM       index.htm

Therefore, you should not have 404 errors, as httrack isn't 
converting names into lowercase when doing the requests ; 
at least this should be the behaviour. If not, please 
provide the bogus URL, I'll check that!