I've received this error as well

HCL Notes/Domino 8.5 Forum (includes Notes Traveler)

Subject:

I've experienced this error since the beta releases, and I still experience it. Although restarting all clients will temporarily relieve the problem, I'm not sure of any more permanent fix, other than perhaps deleting (or moving) the data out of your workspace folder. Before deleting the entire workspace folder contents, you can try just deleting the logs folder (C:\....\Notes\Data\workspace\logs) which in some cases has proved beneficial for me with other issues. I'm having to do this again as we speak. If the error persists, perhaps I will open another ticket with IBM (I have others that are still unresolved for 8.5).

Feedback response number WEBB7PZR85 created by ~Lily Deskroverflar on 03/10/2009