Here is a simple fix for the install....
After extracting the files to a folder but before running Setup.exe,
overwrite the msvcrt.dll file in this folder with the one (good one) from
the system folder. Then install...everything works fine !

If your msvcrt.dll is already corrupt (that is you've already installed IB
and then found other application don't work, then I suppose the work around
Randal suggested should work. That is backup the good msvcrt.dll and restore
it to the system folder.

I'd like to try reinstalling IB with the good msvcrt.dll before I try this
since all it means is that we need to have the msvcrt.dll file updated in
the original download from the IB site (and mirrors).

Whew ! I can finally see "the light". Now I've just got to get to the end of
the tunnel :)

Shiv.