Logon script fails to run

Network OS = 2 DC using 2000 others NT 4.0 SP6a
Client OS = Win 95, Win 98, WinXP
Logon Script – Maps network drives and synchronises time with server

The Logon script fails to run on some Win95 & Win98 workstations on an intermittent basis.
Win Xp workstations cause no problem.

Current resolution is to run the Logon.bat file from the desktop which works without further username or passwords.

Sometimes by logging off and using the “logon as a different user” option will work.

Help for this inconsistent and annoying problem would be appreciated