If you are using SharePoint 2010, and you are trying to open an Excel file from a list, AND you come across the error above (also suggesting that you “Wait a few minutes and try performing this operation again”), the solution may be easier than you think.
I came across many suggestions on the net to restart the server. However, I usually leave that until I’ve tried everything I can. In this case, I found something first and didn’t need to restart it.
The solution for me was to merely restart IIS. It worked!
All Things DotNet Discussed – Winforms/ASP.Net/SharePoint/WPF