My Excel 2007 gives this message (OLE not available) when I start Excel.
I have a windows service running which uses Microsoft.ACE.OLEDB.12.0 but that does close the resources afterwards and even when I reboot the machine, I keep getting this error, even when the windows services (which uses the ACE) has not been started yet.
guest OS is windows 2003 SP2 by the way.

Excel version: 12.0.6654.5003 SP2 MSO 12.0.6562.5003
Can this occur when I build the service on a 64 bit system? I have defined x86 at the build configuration in Visual Studio. The server is a 32bit server.
Edit: I have tried to launch Excel with this ignore DDE checkbox checked:
http://excel.tips.net/T003046_Ignoring_Other_Applications.html