But why that file is missing even after a reinstall is still beyond my understanding

It may well be that, whereas the 2003 version needs bufferoverflowU.lib, the 2008 version doesn't.

Because ActiveState build with 2003 and because that compuiler needs bufferoverflowU.lib, bufferoverflowU.lib gets listed in $Config{libs} and $Config{perllibs}. Once listed there, it needs to be locatable (even if the compiler you're using, or the task at hand, doesn't need bufferoverflowU.lib).

I didn't think of it when I posted yesterday, but an alternative fix for you may well have been to simply remove 'bufferoverflowU.lib' from the libs and perllibs listing in Config_heavy.pl.

These are the sorts of things one has to look out for if one elects to use a compiler other than the one that was used to build perl in the first place :-)

Cheers,
Rob