I, too, have received this error message twice with 0.7: "Run-time error '35601' - Element not found." (Windows 98 SE, with critical updates)
A DLL conflict wouldn't surprise me, especially since I'm regularly running the Visual Basic development environment. However, the error occurred last night while I was downloading, with no other apps running.
One other note: after acknowledging the error, Gnotella still appeared in my task list and in the taskbar tray, for at least another 1-2 minutes. However, I couldn't open Gnotella by clicking on the tray icon.