Double Click, Open, Import result in EMPTY PAGE

I did read thru other postings on this subject, hence I did try to solve the problem with "Import" instead of "open" (Thanks to those users offering that advice, unfortunately that did not work either.)

Am trying to help a friend of mine, who can no longer (at least currently) pay for a designer in his company. His last one passed away unfortunately, so I can't even ask her.
His previous designer did all the logo-work for his clients on Corel 12.0 - just like I am also using.
Got a big HD with all his files, but can only open some, very few actually, most result in a blank page.

File sizes are not big (simple, vector drawings, logos, but a PITA to recreate them myself!)
Did try the following already:

In the directory on the drive: (It says "Coreldraw 12.0 next to the filename and is a *.cdr) Double Click => results in: Corel is opening, but with an empty page.
.....upon closing it does ask me if I want to "save the changes" (Hell no!)

Opening Corel first and than Go to "File/Open" results in the same thing like "File/Import":
I do get an error message (in German) that translates roughly into:
"(file) can not be imported because it is not supported by the selected filter or the file is not supported"

Happens to file sizes from a few hundred KB to approx 2MB (max!) ....and I dont recall having ever defined some "special filter".

....and this also happens to my own Corel-files, from verious HD's, from various versions and ages and even on various PC's ...some of which would really be a pitty if they were lost forever, but currently I really am trying to help my friend.
Can anyone of you fine Ladies and Gentlemen help me to solve this?