I have had the exact same thing happen. I have yet to solve the
issue. The categories  part on the main page  works, but the categories
are not visible on the Categories Dashboard. I also have a part  that
lists the 5 most recently  published documents, and that shows "Query
Failed".

We're having the same problem with the Recently Published Documents
Web Part intermittently giving a 'Query Failed' error. We can get it
working again by flushing the application cache. This leads us to
believe it's a caching problem, although we've not been able to fix
it. Also we have the same Web Part on a different server  and it's
worked fine for 7 months (that Server doesn't have SP1 which
introduced some caching 'improvements'). Did you fix the problem in
the end? As you say any help would be awesome as it's a real pain.

I am having a problem with a web  part suddenely failing  to work, not
sure it is the same thing though..... I have posted this seperalty
but then I saw this thread.

It is the standard web links web part. The 'new and organize' web
part interface at the top is missing so I can not add/change my
links.

I am logged on as a user who is a co-ordinator. This problem has
only just occured, the web part  interface used to be there. This
problem is the same for all web-links on my site.

I have tried deleting the individual web parts  and adding them
again, but that made no difference. I figured it was somekind of
security issue.

I wonder if we tried this: export all of the Web parts  on that dashboard.
Delete the dashboard. Recreate the dashboard  and then import the Web parts
into the recreated dashboard.

I have not studied the VB code in the two Web parts (the Categories Web part
on the home  page dashboard is much simpler than the one for the Categories
dashboard) to know very well how they accomplish their task. But I also
wonder whether the problem lies elsewhere - with indexing perhaps? I'm just
not sure what's happening now.

I'll share the solution when I learn of it!

I had the same thing happen and we rebooted the server  and it went away.

I have rebooted the server, even ran the
Category_Sort.vbs tool to "shake-up" the categories  some.

Still they aren't showing up on the Categories dashboard, but are
showing on the main page.

There are other workspaces on my server, but those do not have this
problem.

Anyone else out there find  a solution?

I would try to delete Category dashboard  and then create new one, name
it Categories and add Categories web  part.

1. Stop the Microsoft Search service. If it will not stop then set it to
manual and reboot the server  2. Delete all files (NOT folders) from the
C:\program files\sharepoint portal  server\data\ftdata\sharepointportalserver
folder 3. Restart the Microsoft Search service (please remember to set this
back to automatic) 4. Test after the index is rebuilt

We started the process, but there are no files
under the folder you specify. It's empty, except of course for another
folder. Is that a problem in itself?