Excel, OLE Automation, and "Call Rejected by Callee"

We have a Delphi 3 application which used OLE Automation to work with Access
and Excel.

Excel sometimes returns the error "Call Rejected by Callee", but the action
completes without error!  This seems to happen more often on Win 95 than Win
NT, and Excel 95 causes more problems than Excel 97.

Does anyone have any idea why this may be happening, and what can be done to
rectify the problem?

An emailed response would be appreciated.