I've copied /albums/myalbum to /albums/myalbum/subalbum
What I've got:
/albums/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum/myalbum/subalbum...

all in all, around 370 (sub-)albums have been created (in /cache as well).
for deletion, i've called the support of my provider.

I guess we will need to know a few more detailed infos about this.

Well, you have initiated a recursive copy. Probably should not have done that

yes it was a recursive one.
maybe in one of the next versions, a recursive copy could be prevented...?

How did you do this copy? Zenphoto does not show me any the album or any of its subalbums in the selecton list when I do a copy.

first I only had "/albums/myalbum" next to others.
then I've created "/albums/myalbum/subalbum", because I wanted to organize the pics.
then I've copied via admin page at /admin-edit.php?page=edit&album=myalbum"/albums/myalbum" into "/albums/myalbum/subalbum" with its copy utility.

Do you have an album named albums? That is confusing since that is also the name of the folder where Zenphoto stores albums.

Did you directly enter that url (/admin-edit.php?page=edit&album=myalbum"/albums/myalbum") The quotation marks are strange.

As I have noted previously, when I try to reproduce this I am not offered the albums folder as a destination to choose so I cannot even attempt the copy.

sorry for the confusion, i don't have an album named "albums".
"albums" is part of the standard installation. the full ftp pathes are:
"http://www.server.de/pictures/albums/myalbum" and
"http://www.server.de/pictures/albums/myalbum/subalbum"

for copying, i didn't enter any url, i just copied it from the browser on which page i've made the copy process and made a typing-mistake. of course it must be:
"http://www.server.de/pictures/zp-core/admin-edit.php?page=edit&album=myalbum"

when i select the radio button "copy" on this admin page (on the upper right corner, it's displayed "Edit Album: myalbum") at the "utility section", i can select any already created subalbum of "myalbum"

one more thing, of course "myalbum" and "subalbum" can be substituted by any other name.

once again, sorry for any confusion. i'm lacking a lot of sleep and concentration due to my new born son...

Ok, we have been able finally to reproduce this.

Fix is in release set 4464 which will be part of tonight's build.