Weird problem in Windows Explorer on XP and Windows 2003

UPDATE

The cause of the problem is found. Somehow something screw up a part of the registry (and it wasn't me!)

Adding the info below to the registry solves the problem. So if you have problems selecting or moving items in Windows Explorer under Windows XP or Windows Server 2003, this might help you too.

REGEDIT4
[HKEY_CLASSES_ROOT\Interface\{0000010e-0000-0000-C000-000000000046}]
@="IDataObject"
[HKEY_CLASSES_ROOT\Interface\{0000010e-0000-0000-C000-000000000046}\NumMethods]
@="12"
[HKEY_CLASSES_ROOT\Interface\{0000010e-0000-0000-C000-000000000046}\ProxyStubClsid32]
@="{00000320-0000-0000-C000-000000000046}"
[HKEY_CLASSES_ROOT\CLSID\{00000320-0000-0000-C000-000000000046}]
@="oleprx32_PSFactoryBuffer"
[HKEY_CLASSES_ROOT\CLSID\{00000320-0000-0000-C000-000000000046}\InprocServer32]
@="C:\\WINDOWS\\system32\\ole32.dll"
"ThreadingModel"="Both"

I have posted this question at the Tech Support Guy forum too. In case you’re not reading that, here it is again. Your help is much appreciated.

=============
I have a weird problem, that you might be able to help me with. Our software is distributed using MSI's. We do regular builds and releases, about twice a month. Now, suddenly reports are coming in that by *deinstalling* our software Windows Explorer is acting weird. Usings cannot select files/folders with a mouse anymore. When our software is installed, all is well.
This only happens on XP machines and I've seen it on our own Windows 2003 server.
Does this give anybody a clue about where to look? How should I go about to find out what's wrong here.
Some background information

• Nothing spectacular has changed in our MSI projects.
• The effects show up only after rebooting after de deinstallation of the software. When installing the software, no reboot is needed to have Windows Explorer act normally again.
• We create the MSIs using Wise version 6, using AutomatedBuildStudio to build and package the software. Nothing hs changed in those procedures.
• The effects aren't present on WIndows Vista or Windows 7 machines.
• I have used VeriTest-Rational Install Analyzer to compare before and after snapshots, but no clear signs of anything wrong there.
• There is one entry in the VeriTest-Rational Install Analyzer log about an entry at HKCU\Microsoft\Windows\CurrentVersion\Shell Extensions\Cached\{2559A1F4-21D7-11D4-BDAF-00C04F60B9F0} {000214E6-0000-0000-C000-000000000046} 0x401 being changed
• There is another entry in the VeriTest-Rational Install Analyzer log about an entry at HKCU\Microsoft\Windows\CurrentVersion\Shell Extensions\Cached\{2559A1F5-21D7-11D4-BDAF-00C04F60B9F0} {000214E6-0000-0000-C000-000000000046} 0x401 being changed
• This already happened before April 1. No relation to Conficker suspected.

ANYTHING that you can come up with is much appreciated.
Thanks for now,
Bart