I had the same problem:
The snapshot location was incorrectly set in the replication properties
the Replication wizard defaults the snapshot directory to something like:
\\ServerName\C$\Program Files\Microsoft SQL Server\MSSQL\ReplData
If you have specified a different directory you will need to set the properties to something like:
\\ServerName\SnapShotDirectory
in Enterprise Manager (EM) you would find this under
-Tools -Replication -Configure Publishing...
select the [Publishers Tab]
select the [...] elipsis of the distrubtion db and set the snapshot folder in there.
That's what worked for me 🙂