Finder-drag'n'drop Stops Working From Time to Time

[alexanderklar]

So, I have finally given up. I am not a Mac newbie, but this is bugging me for about a year now and I have not found a solution. From time to time my Finder's "drag and drop" feature suddenly stops working. Other applications sometimes also do special things from this moment on:

FreeHand MX crashes as soon as I start dragging something like a color field in the palettes (dragging of graphical objects and everything else works as normal)
InDesign CS doesn't let me drag and drop anymore
ImageReady reports "Could not move layer because a system error occured (Error #-4960)" when I try to drag a layer

But other applications don't seem to be bothered:
Mail.app 1.3.11 still let's me do everything (even drag and drop)
Transmit works also with drag and drop
Cyberduck as well

I have researched a lot in forums and so on but have never found a solution. Here at macosx.com I found a hint that I should delete the icon cache and other preference files. I have done that - and had done it with IconCacheCleaner before. Nothing happened.

Also I have re-installed the "coreservicesd" - although it never made a problem (at least it was always visible as a running process in the Process Viewer.

Logging out and re-logging in let's me drag and drop again, but it's rather bothersome to do several times a day. Also I can fast user switch to another user - and there I can do everything as normal. When I switch back to my user I can't drag and drop anymore.

Also I have realised that the problem always appears when InDesign CS is running - and often times Quicksilver crashed when the problem occured (but the latter doesn't happen anymore).

I am eager to find out what is causing this problem - but I don't know where to look anymore. If you can help you are my Mac God.

Thanks and nice greetings from Germany,
Alexander