I could be wrong, but I dont think mIRC's $disk identifier is ment to be used the way you are trying to use it.
from the help files:
Quote:

$disk(path|N)
Returns information about the specified hard disk, where N = 0 for total available drives, and N > 0 to access each drive.

Properties: type, free, label, size, unc, path

$disk(c:) returns $true if drive c: exists, otherwise $false

The unc property returns the path for a network drive.


all it is for is mounted drives, hard disks and CDrom drives, not folder Anything.
the Path you see is relating to a Networked drive not a file path.
maybe what you want is in other identifiers
$exists(file/dir)
Returns $true if a file or dir exists and $false if it doesn't.

$exists(c:\mirc\mirc.exe) returns $true or $false.

$file(filename)
Returns information about the specified file.
Properties: size, ctime, mtime, atime, shortfn, longfn, attr

$finddir(dir,wildcard,N,depth,@window | command)
Searches the specified directory and its subdirectories for the Nth directory name matching the wildcard specification and returns the full path and directory if it is found.