sharing experiences…
Since a week, all of a sudden, I had this very strange problem that I could not move email items from the message list pane to a directory in the left pane. I got this error:
“Can’t copy the items. An OLE registration error occurred. The program is not correctly installed. Run Setup again for the program”
When you try to uninstall Office 2003, the following error may occur
This patch package could not be opened. Contact the application vendor to verify that this is a valid Windows Installer patch package.
I faced this error yesterday, after a failed upgrade to Office 2007. My computer hang at the point “uninstalling office 2003“.
After installation of Adobe Professional 7, 8 or 9, you may get the following error when you start Word 2003 or Word 2007:
“Compile Error in Hidden Module: Autoexec”
The cause of this error is PDFMaker.dot, which loads at startup. Since Adobe Professional 8 uses DLL-addins to add the toolbar in Excel, you can safely delete the PDFMaker.dot file on your computer.
Sometimes PDFMaker.dot is located in your profile directory:
C:\Documents and Settings\<user>\Application Data\Microsoft\Excel\XLSTART\PDFMaker.dot
Other times, PDFMaker.dot can be located in your Program Files directory.
If you have installed Excel 2003/2007 and Adobe Professional 7, 8 or 9, you may get the following error when you start Excel 2003 or Excel 2007:
"Compile Error in Hidden Module: Distmon" 
Cause:
The cause of this error is PDFMaker.xla, which loads at startup.
When you have set Word 2003 as your default e-mail editor, you might get the error “Interface not registered” when trying to send an email. You are still able to send messages with the Outlook editor set.
To solve the problem which causes the “Interface not registered“-error, do the following