Excel... "the clipboard cannot be emptied" - a solution

I say "a solution" advisedly: Excel warns that another application may be using the clipboard - thereby preventing it being cleared (because e.g. the other application has "locked" the clipbaord.) But even if it were true, how does one identify the offending app? The hard way... quitting them one by one and seeing when the fault goes away. As a result of which I found an offender: the Skype add-on for Firefox - and whilst other applications have also been noted as being at fault, the only one I had previously noted was rther more obscure than Skype.

I had tried all sorts of cleverness (such as adding DWORD AcbPreventPreemptiveCollect = 1 to HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Common\General; checking that rdpclip wasn't running; worrying about the VM integration features of Windows 7's XP Mode, etc.), none of which worked, and then for some reason just thought I'd be methodical with the only other major app that was running - FireFox.

I restarted it in safe mode and the Excel error (which actually only affected Drag and Drop, rather than cut and paste per se) disappeared. I then went through the Add-ons disabling all and re-enabling one by one until the culprit was found. To be honest, I had expected the Adobe Reader plug in to be at fault, but it wasn't.

Hope that helps lots of people with various clipboard problems in various versions of Excel and various Microsoft operating systems.