Version:           2.3.0 (using KDE 4.4.2) 
OS:                Linux

My collection folders are on an a external USB disk (NTFS formatted).
I selected two folders ("2 listen 2" and "Mp3s"), both are subfolder of a parent folder called "Music".
The folder "Music" also contains a folder called "Old", but it is not selected.
Sometimes (probably when I add any mp3s in these 2 folders) I find in my collection a lot of (not all) files contained in the "Old" subfolder. Recently I found (in my collection) also files in the hidden Windows recycled-bin folder stored in my external disk!!!
After I execute "Full rescan my collection" the unexpected files disappear (but sometimes it takes me to manually remove from the collection also after a rescan!).

[Sorry for my English!]

Reproducible: Sometimes

Steps to Reproduce:
Include (in the collection) only two subfolder of a parent folder containing other subfolders. The folders are stored on an external USB disk.
Enable the option "Scan folder recursively" and "Watch folders for changes"

e.g.:

Parent Folder
|
|-[X] Folder A
|
|-[X] Folder B
|
|-[ ] Folder C
|
|-[ ] Folder D
.
.
.

Actual Results:  
Some files of excluded subfolders are listed in the collection.
Sometimes also files contained in other folders (not subfolder of the parent folder) are in the collection.

Expected Results:  
Only files (or a subset of) contained in the selected subfolder should be listed in the collection.

OS: Linux (x86_64) release 2.6.32-23-preempt
Compiler: cc