You may face an error while opening a specific file type (eg. .xls) in eclipse.
Cannot create the in-place editor
This is probably because there is no OLE editor registered against the type of file you were trying to open.
Open Window > Preferences > General > Editors > File Associations.
Add *.xls and add Associated Editor (from this window you can select external programs to open with).
I think you be able to open the excel file inside and eclipse editor, but it looks like the OLE is not working on your system for some reason.