FTP cannot write error

I am experiencing an intermitant error when trying to FTP to a webMethods IS 4 service running on Windows 2000.

We are FTP’ing fine for a number of days, but then out of the blue we receive the following error.

553 ‘EVENTS.XML’: cannot write.

We fix the error by simply renaming the service, and then changing the name back to the original service name. It then works fine again until it decides it wants a name change again.

has anyone seen/fixed this problem?