subversion checkout/merge issues

I hope someone can help me here.

I have an svn repository (1.1.x) running behind apache on Windows 2000, and
It's been fine until today, but then I started getting these error messages
when I try to check out a branch of my code on my Windows XP box.

svn: Can't move 'C:\cms2-3\blah\workDir\.svn\tmp\entries' to
'C:\cms2-3\blah\workDir\.svn\entries': Access is denied. (using svn
1.2.3command line)

Error: Can't move 'C:\cms2-3\bat\.svn\tmp\entries' to
'C:\cms2-3\bat\.svn\entries': Access is denied. (using tortoise 1.3.0 -
just upgraded yesterday)

The checkout runs for a while, then seems to stop at some random point and
wait, and then I get the messages. Using TortoiseSVN, I see that the "bytes
per sec" drops to zero for a little bit before the error message occurs.

I eventually ended up restarting the machine where the repository lives, and
was able to check out the whole project and do a dry-run merge, but then
trying to do a real merge is crapping out and leaving the system in a locked
state. I do a cleanup and it tells me that it can't find a file that it
needs to delete.

--
Nervous passengers are advised to wear a blindfold.