ARCServe 2000 and open IIS files

In using ARCserve 2000 to back our IIS webservers, but several files are being seen as open and are not getting backup. CA has been of little help trying to figure out why image and web files are not getting backed up. Has anyone run into this time of probably and how have you solved it.

Tech Info:
ARCserve 2000 running on Windows 2000
Windows 2000 with IIS 5.