Cannot save files to network drive with MS Office 2007

I recently upgraded MS Office 2003 Standard Edition to MS Office 2007
Professional Edition. When attempting to save new Word, Excel, or Powerpoint
files to a network drive I get a message ' "drivename\foldername\filename"
cannot be found. Check your spelling, or try a different path.'

I can save new files to local drives, or I can retrieve existing files from
network drives and save them back to the network drive under the existing
name.

I've triple checked path names, My Document path, the Save menu option, and
Trust Center settings. Does anyone have any suggestions as to what I'm doing
wrong.
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JDBrock