Could be, but like in the previous thread the poster said, it's difficult to say. At one point or another during a long session I come to the conclusion that drag/drop doesn't work.
In my case it's always happening on the desktop. So I doubt it could be caused by a program.
What happens is that I drag a file or another folder above a folder and the file or folder won't merge into that folder but slips aside.
It's as if I drag a file/folder but drops it next to the given folder.
And after a restart it's solved. But restarting my Vista ! Sometimes it takes 15 to 20 minutes. Luckily not always. Vista likes to surprise you. I've learned in the meantime that I never should stop or break up an operation. Even if my Vista needs 30 minutes to shut down. This would cause the so-called cross-linked files to appear. After which you will have a hard time to make a partition on your HD.