Recently I came across an issue with our internal deployment of SharePoint 2010 Enterprise. We are taking full advantage of Excel Services and opening documents in the browser. A user emailed me with an error that said “Excel Services is unable to process the request. Wait a few minutes and try performing this operation again.” Upon checking the ULS and Event ID logs it had an Event ID of 5240.
Upon searching the webs I came across a couple of TechNet forum posts that talked about rebooting the server to rectify the situation. However, later on in the forum post it was commented that it would work temporarily and the error would come back again.
Luckily I ran across a blog that talked about this issue and a fix without having to reboot the SharePoint server. The Point Beyond website talked about logging onto the server with the account the error displayed to create a User Profile on that server. This should rectify the situation. Low and behold that did work, temporarily. I will let you know if anything changes. Of course I do wish the blog mentioned why it worked, but that is another time. Good luck!