I'm on Vista running WinHTTrack 3.43-9.

Since I couldn't answer your question, I tried it myself.  When I did a "pause
transfer" while running a mirror, Vista wouldn't let me delete the hts-log.txt
file.  I couldn't even delete it from an escalated command prompt.

However, from an Explorer window, I *was* able and permitted to do this:
a. Right-click the log file,
b. Choose Properties,
c. On the General tab, click the Advanced... button,
d. Check the box labeled "Compress contents to save disk space",
e. Click OK.
f. Next click Apply and and you can see the reduction in space used by the
log.
g. Click OK to close the Properties window.

My 400KB log was reduced to 100KB.  Of course, this assumes you're on an NTFS
filesystem and don't have compression disabled.  You *could* probably do this
without pausing, but I would not suggest it.  I don't know if trying to
compress the file while it's being written to would introduce corruption.  Ask
an NTFS guru if you're really interested.

On the other hand, if deleting it is okay with you, it sounds like you don't
need the log - at this point, anyway.  Before you start the mirror, go into
WinHTTrack's "Set Options..." to the "Log, Index, Cache" tab and UNcheck
"Create Log files".  If the box is checked and anything other than "normal" is
selected, that would explain why the size of it is out of control.  If
"normal" (the default) is not already selected, try running the mirror with it
set to that, unless you don't want to mess around with it and simply disable
the log.

Not saying I don't believe you, but I have to wonder if some other setting is
incorrect if your log file is actually taking up more space than the mirror
itself.  From that I would infer that numerous unnecessary server requests are
being made and you are using inefficient filters.  You might want to read up
on "Advanced Filters" or post your attempt here for input.

If you already have a basic understanding, look here:
<http://httrack.kauler.com/help/Home>