Missing Library?

I had to reinstall Excel2000 after a serious mishap last week. But now I find that some of my Excel spreadsheets, which contain a lot of VBA code, do not run.

A simple assignment code (e.g. Abc=123 results in a "Can't find project or library" error message (see attachment).

Strange thing is when I create a new spreadsheet and enter the same code, it works fine.

Please help!

Thanks