Weird vista problem

Today I had to unzip an archive so I double clicked the file, copied the
content (CTRL-C) and then pasted my stuff into another folder.
The problem is Vista refused to copy the full content of the folder
since there is a folder which got the same name than a file at the same
level and I'm told something like 'There is already a file with the same
name you have specified for a folder. Change the name'. That window
provides me three buttons: try again, ignore, cancel.

My vista is a Home Premium SP1 perfectly clean in every way. It runs on
a new laptop acer gemstone 5920.

When I got that weird message I tried to create a folder and then a file
with the same name the folder has, at the same level: Vista doesn't
allow me to do so saying: A folder with that name already exists. Change
the name (and two buttons: try again, cancel).

At work, I try to perform the very same test on another laptop running
Vista Home Basic (not SP1): it worked perfectly.

I do know that works also on XP (whatever version) and Linux (on any
distro).

So my question is: is it a known issue on Vista SP1 ? How to fix it ?

Thank you