$string=\\Server\user;

Syntax error. Add quotes (And note that \\ will evaluate to a single backslash).

@tmp=split(/\/,$string);

Syntax error. The backslash escapes the delimiter, leaving an undelimited string.

Does anybody have any suggestions?

Try posting the code you're working with (but only relevant bits), instead of some broken examples. Learn about using the <code> tag too.

U28geW91IGNhbiBhbGwgcm90MTMgY
W5kIHBhY2soKS4gQnV0IGRvIHlvdS
ByZWNvZ25pc2UgQmFzZTY0IHdoZW4
geW91IHNlZSBpdD8gIC0tIEp1ZXJk