Note: this is neither a
Java question nor a beginner question. The Web pages may be generated by Java, but that's almost certainly got nothing to do with it.
If your stated observations are indeed correct, then what is happening might be due to the different types of data being posted to different applications.
When you Copy something onto the clipboard, the application from which you are copying (IE in your case) can decide to put more than one version of the data onto the clipboard. For instance, it could put plain text and HTML. More importantly, it could put some Microsoft special linking object (OLE or whatever's the current thing - I'm out of date on MS) on the clipboard that would call back to the originating application when pasted.
When you paste into Notepad, which is a dumb application, it can probably only accept the plain text version.
When you paste into Excel, which is a Microsoft application with all associated bells, whistles (and bugs?), it can probably accept all the different data types, including the special linking object perhaps. Therefore, pasting the data into Excel might cause calls to be made from Excel to IE, to get data or metadata. Maybe there's a bug in this process that causes the session to be expired.
If that's the case, you could work around it by using Paste Special, instead of Paste. When you do Paste Special, it gives you a menu of all the types of data on the clipboard. If you choose something simple like plain text or HTML, the problem might go away.
[ June 08, 2006: Message edited by: Peter Chase ]