Faster DirectoryExists function?

I use

DirectoryExists (const PathName : String);

to check if a directory is reachable from a computer or not. But if the directory does not exist and the path name is a network path, i.e.

\computer1Data

the method takes a very long time to return.

There must be a faster way to determine that a network folder is not reachable. Or can I configure some timeout parameter that DirectoryExists uses internally (I looked at the source code but it just delegates to GetFileAttributes which is defined in kernel32)?

Any ideas?