Unable to merge offline changes on '\\servername\path'

When I go to synchronise offline files I get the same message keep popping
up, and synchronisation fails:

Unable to merge offline changes on '\\servername\path' The parameter is
incorrect.

I have looked on the internet for solutions and found that I need to hold
the Ctrl+Shift keys down while clicking Delete Files... in Folder
Options-Offline Files. That seemed to work ok, after doing so was able to
synchronise without any problems. Now, a day later the same problem has
returned. Anybody have any ideas what could be causing it. I am logging on
to a Windows 2000 Server via wireless network using Windows XP Profesional

Any help much appreciated.

Thanks